The Expert Reviewer for mime type registrations is Ned Freed, so he has the last say.
That's correct for types registered through the IANA process. Since these types appear to be the standards tree (no vnd. or prs. prefix), that requires IESG processing, which is not my baliwick. FWIW, in the case of IANA registered types, my job is to apply the criteria spelled out in the relevant registration procedures. AFAIK there isn't a lot of guidance in there as to when it's appropriate to use multiple types versus, say, a single parameterized type. So, absent a clear indication that what's happening are multiple types being defined for the same thing, I would allow all three types to be registered. But as I said, these are standards tree registrations so it isn't my call in any case.
My personal opinion is that either one or three types should be fine, and that probably the WG has the most expertise to decide this, but that you should really consider what others on this list (in particular Mark) said.
Mark's point was, as I recall, the presence of +mathml in the type name. That is indeed somewhat problematic and I would ask it to be changed if I were the reviwer. A -xmathml+xml suffix would be fine though. Ned