Nothing in the OED entry for 'maven' suggests that it can't be used for either gender.

Yes, it's very irritating to have a name that the Americans have feminised.(But isn't Robin Williams an American?) It's clearly going the same way as Hilary and Jocelyn. (And someone tried to tell me not long ago that Augustine was a girl's name, and that it should be pronounced AUG-us-TEEN, rather than Aug-US-tin.)

I tell you, chaps, they're taking us over. First vicars, then Morris dancers, and now they're pinching our names .... where will it end?