I assume not, but thought I'd check before wasting my time on his questline (if he has one that is)

and similarly if you do keep it, then I best get to work on his questline quick!

Yes, all the companion perks are permanent. Once you have it, you have it for life like herpes.

Nice! Well since I probably won't bother to play the game again as a BOS soldier, looks like I'll be dancing with Danse!