although he had to come back at the bottom of the list as an f/o (as it should be).
Ah yes...that Seniority chestnut. Working to make sure that once you leave, there is no chance you'll be back unless absolutely desperate. And also making sure that QL can't access experienced captains.
I assume the captain referenced above won't be hanging around for long when he/she can just as easily get on the bottom of the seniority list with another company for better pay.