Unfortunately, I think there is a point, where the math font encoding (here:
MC) needs to be changed for the sake of compatibility.

Currently it is possible and often applied practice, to use

\( \mathit{\Gamma} \mathrm{\Gamma} \mathsf{\Gamma} \)

to get the different shapes of the capital greek Gamma. The MC encoding as
outlined by Justin Ziegler makes the capital Greek letter mathematical
symbols (instead of mathematical letters) and treats them in a way entirely
different from Latin letters. I cannot imagine any sensible implementation
of \mathit and friends with the current MC encoding.

THe MC encoding currently puts upright and italic greek (both upper and
lower case) in one encoding, thus disabling the commands like \mathrm and \
mathit for capital greek letters.

--J"org Knappen