Sorry. I don't know.
Rudiger Schaper has theories
that could be interpreted as touching on that possibility
in his Simonides Biography.
There's the "tripotages"
comment from one of the Athos monastery's about his behavior among the male only inhabitants, which can have a sexual connotation attached to the word. But whether that was meant, or just the generic misbehavior, is simply open to speculation.
- He didn't marry.
- There's no talk of mistresses or girlfriends (that I've seen).
- But there's no talk of homosexuality (at least that I know of) either, in the contemporary accounts I've read, so far.
I have to admit though, that, when reading the American missionary guy (name?) persecutions in Greece, in the early 1840's, Simonides tried to pin the false accusation of "orgies" on what's his name (sorry forgotten right now - it'll come to me later, Jonas something?), and I did wonder if he was projecting his own behavior onto this guy
(as has done to others at other times). But that's nothing but pure speculation, for which I have no concrete evidence.