Hindsight being 20/20 and all....it would have been to Esplin's advantage to have the morphing power in the long run, as it may have led to a possible escape route post-war. However, since he did not think to do so....
Anyhow, I don't think Esplin OR Alloran were ever at risk. I imagine he had his own personal Yeerk Pool that was probably in his quarters. He could just lock the door, restrain his host, and feed to his sluggy content. He could probably even set it up so that if anyone tried to enter his room mounted Dracon Beams would immediately fry their sorry butt.
As for in #8, I think that was more of a fear thing. Stupid, mindless underlings not taking advantage of a situation that they could take advantage of.