How in the hell did you catch such a tiny ball with that little stick? hell I was called "crotch killer" when i played baseball because i kept hitting the pitcher in the balls, i sure as hell couldn't whip a ball that small and get it close enough to that little stick for anybody to catch squat LOL!
And your nephew is right and wrong at the same time. yes you DO build up calluses but if you play 4 string for a long time you get a thinner flatter callus and then when you play a 5 string, especially one with the really fat strings like I like, its gonna tear those calluses clean off which is why I'm typing sans fingertips. On most basses the top string is between 102-105mm, whereas on my 5 string its 130mm. That much wider string means much thicker windings which requires a different style of callus. after a couple weeks of playing the 5 exclusively I'll get fat round hard calluses instead of the thin slicks I had playing my acoustic 4 string.
But honestly when the music is cooking you don't even feel it. when my last band won "best band in state" the crowd was going apeshit as I was tearing into the last 5 songs and when the set was over Isaac (the singer) leaned over and said "Jesus Christ man, don't that hurt?" and I looked down and that pearl white pickguard was streaked red with blood. i have been ripping into those strings so hard it literally ripped the calluses clean off my first two fingers on my right hand. But the roar of the crowd and the rush from the music had me so high i honestly didn't even feel a sting, the rush was just too great for pain to even enter into it. The next day i used half a bottle of superglue to make a scab for the missing skin and was right back on stage that night like nothing ever happened.
But you should pick up an instrument and give it a whirl, its never too late to pick up. if you were able to whip a ball around like that playing a keyboard wouldn't be hard at all, tons of tutorials online and you can get a cheap board for a little of nothing. Or get your nephew to show you some of the basics like the box pattern on the bass, nice thing about bass is there are a ton of easy songs you can play when you are starting out, AC/DC and Judas priest bass lines are some of the simplest lines ever written but they are catchy as hell, then you can always work your way up later to the harder stuff like Rush.
Just remember NOBODY is perfect, there will ALWAYS be somebody better, hell I've been playing for nearly 30 years now and there are still some Rush songs my stubby fingers will never be able to play, YYZ or La Villa Strangiato (which is pretty much the hardest song ever recorded, i know plenty of guitarists and drummers that have also tried and failed that one) just a couple of examples. but just because there are others better doesn't mean i can't get a crowd to bouncing and THAT is ultimately what matters. When you have the crowd jumping and the music is pumping its unlike anything words can describe, its like an electric current joining you to your band and to the audience. i have actually had to watch videos of myself because we had a killer crowd and what i was playing was frankly beyond me, it was the energy from the crowd that made me better than i was.
BTW I don't know if I gave you this link or not but if not might want to forward this link to your nephew and if you want to play guitar or bass check it out yourself. these guitars and basses are cheap but good, they of course won't compare to say a $1000 Fender or even my $700 Squire but they have good tone and since they copy fender and Gibson you can customize the hell out of 'em dirt cheap. In my last band we would get cheap instruments like this to give away during raffles but these sounded good enough the guitarist ended up with half a dozen and I had one of the jazz basses for ages until i got hooked on 5 string and swapped it for a second 5 for a spare.
But I'm telling ya man you gotta try it at least once, hell if I could walk out onstage not 2 weeks after starting bass to play a 2 hour show (thank God it was mostly AC and blues or I would have been screwed!) then anybody can do it. Keyboard is easy, beginning bass is easy, hell even guitar if you go for rhythm instead of lead is easy, and trust me when you finish that first song and the crowd is roaring you will have the biggest shit eating grin you could ever imagine, nothing comes close. Nearly every town has a place with open mike nights, pick up 2 or 3 rocking blues tunes (blues is not only the basis for rock but is also one of the easiest patterns to learn, a good 70%+ of songs use a I-IV-V pattern) and just go up there and have a fricking ball. If my 45 year old ass can do it you can too. I'll likewise never be able to just sling myself across a stage like I did when I was 20 but the nice thing about music is nobody gives a shit as long as they are having a good time. look at John Lee Hooker, the man played on stage until he was in his 90s.
Anyway give it a shot, if you can program there is no reason you couldn't pick up something like keyboard or bass, its all about patterns no different than how programming has its own syntax that once you learn it is easy to follow. Its a blast man, worth every second.