With enough work from a gunsmith, lots of things could accept modified AR parts. That doesn't make them AR's or AR variants. I think that most of us could come up with a laundry list of different rifles (and shotguns) that can be modified to accept at least some AR parts. Many of those modifications don't require a gunsmith's attention. I'd say that as long as you can't interchange receiver groups then there's enough of a difference that it shouldn't be a variant.
Of course, this is a common sense statement. There's nothing assuring us that what we see as common sense will be part of the criteria for determining the status of the Masada/ACR.
We can only hope that the difference in appearance, the lack of direct lineage, and the fundamental difference in design and function will keep the Masada/ACR design unrestricted as long as it has an appropriate barrel length.
Although it'd be nice to have an XCR with a couple different barrel lengths, I can absolutely see where Wolverine is coming from. A good part of the appeal of the XCR is the fact that it's non-restricted, and it would only take a couple examples of people doing inappropriate barrel swaps to start raising red flags with CFC and the RCMP. That would hurt Wolverine financially and hurt existing XCR owners as well.