In Martin's SUSY Primer, he claims:
For the higgsinos and gauginos, [the ability to have a mass term] follows from the fact that they are fermions in a real representation of the gauge group.
As I understand it, in the Standard Model, explicit fermionic mass terms are prohibited due to the chirality of fermionic fields, i.e. the fact that they transform differently under $SU(2)$ symmetry. I believe this constraint is essentially imposed on the theory by the empirical observation of maximal parity violation of the weak interaction.
So are higgsino and gaugino mass terms allowed in the sense that we have no empirical evidence of a similar constraint such that it's still possible (though not certain) that such mass terms are allowed?
I also don't understand what Martin means by the fact that higgsinos and gauginos are in a "real representation of the gauge group". Why is this not the case for SM fermions?