Ok guys, here's what I found on Lolth's page on the FR wikia:
Lolth's clerics were almost exclusively female (although there were a few males).
The Militant Myrlochar, sometimes known as the Order of Soul Spiders, was an elite fighting organization composed exclusively of male crusaders, and found in the dark elven cities where Lolth was worshiped and males were allowed entrance into her priesthood. They directly served the reigning Matron Mothers of the city and were employed to kill their targets. They were usually used without pause until they got killed.
So while I agree that a male cleric of Lolth seems bizzarre, apparently it is not against established lore - just very rare.
(Though I think male clerics of Lolth should get appropriate reactions. It IS weird in most places that have even rudimentary understanding of drow society/religion - including most drow cities, I presume.)