Unlikely to be a 90 degree deviation and it occurred after the pitch up.
Having no idea of the exact Wx that he was facing, I have no idea what his deviation was likely to be. I have no idea why 90 degrees would be more or less likely. However, the radar plots which have been doing the rounds lately show a left turn initiated at 23:16.52 at FL320 and rapid 'climb' starting at 23:17.18 while still at FL 320.
And climb was most likely because he was below optimum for such a short flight.
it has been stated many times that his increase in FlL request was denied. It's highly unlikely that he would initiate a unauthorized climb to move up to optimum .