Of course not.
With a closed-source binary, we can try all permutations of USB drivers, dongle drivers and debugger drivers that we can get hold of (and that's exactly what we did). Anything beyond that is impossible.
With an open-source program, we can start by instrumenting allocation / disallocation syscalls, and look for the mismatch. Narrow it down step by step, until we find the missing disallocation that causes Windows to run out of kernel RAM. Just like we do when debugging our own software. Honestly, I've put my head much too far into things I shouldn't have to care about, I'm quite certain I could have solved that together with my coworkers. Now we just have a permutation of drivers that usually happens to work for an 8-hour work day, and don't know why.
Of course it can take a day or two to get the open-source thing to compile at all. But I'm quite certain we've lost much more than one or two days to dongle problems.
So far the minimum seems to be filling out lengthy forms (aka performing data striptease). Some will then give you a demo, some will after reviewing it by a human. And others only have "call us and we'll make a deal" (which includes signing contracts).
For open-source, you grab a tarball and are ready to go. And it's not a crippled demo, it's the real thing.
The GPL does not restrict your rights in running software, whereas running it usually is the only right you get for closed-source. So the GPL cannot be "highly restrictive" compared to closed-source.
Stefan