Correct, he temporarily lost his job class position, he never lost his seniority.
Also, since he was out 7 months, it's quite possible didn't bid on the bi-annual Jan bid, therefor, when he returned to work and if there was a spot available, he would've dovetailed onto the extra board by his seniority. A bump bid would've occurred only if the bi-annual bid was more than 30 days out, which it wasn't. If by chance he did bid in the Jan bi-annual bid, upon his return and providing his spot was still available, he would've returned to his bid, and again, a bump bid would NOT have occurred.
Since you're a city driver, I don't expect you to know the policies concerning the road but if you're going to attempt to call me out, you may want to brush up on those policies first!!