As far as I know, there is no legal reason why they would. but I would assume they have the ability to do so.
The main question is, what is the integrity if the people making the iso. Have you tried making an ISO of a legit copy you own and seeing what essentials does to that?
But I wouldn't put it past M$ to download a bunch of illegal copies of their product, and find a few identifiable features about them (checksum) and make it so the scanner flags them as potentially dangerous.
I do know that you can suggest the scanner ignores that file once it is noted as bad.

And sorry about the late response. Had a password issue .