Look at the picture. And some competitive lifters use less-than-optimal technique. So what.
i dunno man, i've watched countless videos of competitive lifters, and i do mean countless, scrutinizing their spines. this is an issue of great concern for me, given my own difficulties with the squat.
one conclusion i've come to is it can be damn hard to tell how someone's spine is really oriented. in that picture, his knees are buckling in, but that's the only thing i could confidently say is wrong. and even then, many o-lifters knees come in at the bottom of a squat when the weight gets heavy.