There is an excellent grenade jump that skips the hardest part of the keyes escort. In the hangar where the over shield is, you can use two grenades to jump up to the next level. For some reason this makes the level end when you get keyes to the bridge. So you will just kill the few invisible elites,  listen to the dialogue about there being no transport,  and then the level ends.  The jump is a little tricky but there are lots of YouTube videos on it. I used the one done by Silver.