How many professionals are asked by their future employer about the work they do for free in their spare time? Would you ask a doctor how many patients he/she treated for free? Or a lawyer how many cases he/she did for free in their spare time? I don't think so...
By all means, I think contributing back to the community is a noble, great thing to do (and we should all strive to do it), but this should not be considered the sole measure of one's technical skills.