"How about writing 80387 compatible core? This way they can't complain!"

But how do you know it's really, fully, truly, compatible?
And if it really is 100.00000% compatible, I'm sure Intel could use that to say, "but how did you know about ... without stealing our IP?"

Even today, you still see terminal emulators that boast about faithfully emulating the bugs in a real VT-100!!!