Based off my reading of the match, I don't think Saanga could, in the time frame, shift focus to launch the javelin-spear of infinite doom, especially not in a pinpoint attack. 

His orientation wouldn't allow for it, especially with the lance being straight down, and his body being straight up. He'd have to adjust the lance, and with the span of time, it makes little sense to try and do so. Better off probably crash landing, rolling to soften the blow, or using the lance to fend off the mech if possible. 

Now, he could possibly launch it, but it would be more of an un-aimed shot than a perfect display of accuracy.