If you check the slides, there are a few areas that they failed hard on. I don't know if you're a C developer, but I've coded a bit, and the slides scared me a bit.
Yeah, there was the "cross platform" stuff. Do we really need EBCDIC support? There's a simple rule about code. If you can't test it, you should pull it. Do you have a machine you can test on? They had Win32 Winsock code, which is a special case. But all modern Windows computers have a Berkely sockets type stack. This doesn't need special code, which means a lot less code to debug.
When the OpenSSL guys state (with some justification) that they have no resources, part of the problem is they waste it by having unused code paths. They'd save some testing time by having removed this code before.
But they also did "cross platform" it badly. They had their own printf, when printf has been done and safe for years. But just in case on some oddball platform, we have our own. They had 17 levels of nested #ifdef. If you don't know C, that's SCARY. There's no way you'd unwind that in your head, and there's near zero chance you'd be able to code a test plan for that. Why? Because you can think of #ifdef as a way of doing simple code modification... 17 levels deep of this type of modification is near impossible to think through and is nearly guaranteed for bugs.
Worst of all, in name of one platform, they came out with an oddball memory allocator. They added things to this allocator to the point where they couldn't run a normal one. Worse off? They got so used to BUGS in this allocator that they couldn't move off of it. And these bugs are directly related to the Heartbleed bug - it's a memory management bug. Instead of thinking "hey, we're doing a lot of weird stuff just for this odd platform" they made the decision "hey, lets go even deeper down the hole of bad code"
So, in name of "cross platform" they had many many design mistakes, including something that broke much of HTTPS. I wouldn't use "they were doing cross platform" as an excuse for their mistakes, because in this name, they had made much of their mistakes.
This wasn't in some text editor. This was in a piece of core crypto. The level of sloppiness allowed is zero.
They OpenBSD folks take their tone from Theo De Raadt, who generally is one of the ruder people out there. When i first heard the rants about OpenSSL, i was thinking "well, they didn't have to smack them down so hard." After reading the slides, Im thinking "yeah, I'd rant that hard" though i don't have the same Forum as the LibreSSL guys have.