Worrying about the legality of the MiniMig hardware is ... almost completely pointless.
The fact is that you could program whatever you like into the MiniMig. It's almost certainly a mere matter of time until someone has setup an Atari clone in one in fact many 68000 based machine could be replicated in it.
It was designed to do the job of providing an environment that the Amiga could be replicated in using the correct software.
Now the software might theoretically be somehow tainted enough that someone might be able to bring a case that got to court... maybe. The hardware however... I just can't see it being possible and I'd lend whatever coding ability I have to reproducing as many 68k based paltforms in the MiniMig hardware as is humanely possible just to muddy the waters if anyone tried :-D
Andy