What was really convenient about him? Had he been a scientist that offered a great deal about the Crucible, then perhaps he would've been, but being essentially a grunt nobody that didn't know any more than Shepard did, while totally ruining Liara's idea of what the Protheans were really like was pretty enjoyable.
And it made sense - the protheans were an imperialistic species, they would prioritize the avatar of their vengeance, someone who is a soldier to the bone (probably bred for it, though that probably takes us into the realm of headcanons for the protheans), someone willing to take on the choices of the cruel calculus of conflict. They wouldn't prioritize a scientist's survival, they wanted a soldier who would lead the fight.
After all, they weren't expecting him to be in that pod for fifty thousand years. He was supposed to be a leader of soldiers, the head of a new prothean empire. He ended up being the last survivor of his species.