No, that was part of the course: "Free warfare".
That's why the 80mm is handy. The 120mm really isn't man portable, and you can't easily store hidden ammunition in suitable spots. The 80mm is readily man portable and can be hidden most anywhere, while it still packs the punch that the 60mm decidedly lacks. In fact as the ranger battalion I did my (shortened due to injury) service in had as it's main mission to perform sabotage and ambushes of the enemy's logistical support train behind enemy lines, I'd say we had "asymmetric" down to a "T".
That said, armed insurrection against a state level enemy having just a few rifles is a pretty doomed affair. Having access to a firearm is probably the least useful attribute of a successful insurgent. Having, or having access to, intelligence, leadership/chain of command, logistical support, counter intelligence and security would be much more useful, critical even.
If you study the resistance movements that were active in Europe during WWII, you'll see time and time again that your options against a determined foe are limited, and firearms aren't a central part of it. In fact you can have a very successful resistance without any firearm. The Danish resistance (and the Norwegian to a lesser extent) for example forbade the targeting/assassination of German personnel as the resulting reprisals against the civilians took such a tool that it made such operations impossible. Instead they targeted their own countrymen that were deemed to be collaborators. Insurgency is a dirty business. So, if you come across such as juicy target that you can't ignore it, you'll want as much effect as is humanly possible, i.e. explosives and some way to deliver them (c.f. the fate of the SS Donau.) Using a gun would have been worse than useless during that operation, and would have led to failure.
So in summary. While having and knowing how to shoot a rifle isn't a completely useless skill in the "stay behind" scenario, it's not a very critical one either. There are many other skills and preparation that you can't do without. You'd probably be better off staying at home reading books than going to the range...