I am afraid you are wrong on two points: there was indeed a license agreement with every Amiga sold (whether enforceable or not, I don't know), but more importantly there were no rights to be waived in the first place.

System ROMs were protected copyrighted works well before the release of Amiga in 1985. See the case of Apple vs. clone maker Franklin:

https://en.wikipedia.org/wiki/Apple_Computer,_Inc._v._Frankl....

What you describe is piracy. Your other comment about legality having a "bad reputation among Amiga enthusiasts" makes it seem like the Amiga community is one of criminals. That is sheer madness.