Piston popped out of caliper...(?)

Hey guys

I'm trying to get my 91 lx running.

This morning a buddy of mine(who knows close to nothing about cars..he was there to crack jokes so it won't get boring lol) and I were working on the brakes.
Both brake pads were out and he steps on the brake pedal.

So naturally the piston was pushed out of the caliper and fell on the floor.

So the only way to get it back in the caliper is to unhook the caliper from the brake line right?
Either way I'll have to bleed the brakes since air will get into the system either way I do it.

Anything I need to be concerned about or watch out for when I put the piston back in?
Sorry....I don't work on brakes much. First time.

Thanks
Patrick

I'll probably unscrew the cap on the MC and try to push it in with the line still attached.

See how it goes.Don't really want to take off the line.

I'll have brake fluid everywhere.

Will do.

Just a shame I don't have one of those caliper tools.
I'll just have to muscle it in.