Unless I am the last one surviving I stay in when I run out of paint and/or air. At worst you can serve as a distraction allowing your team to take out a few more players. You could even help your team win the game just by staying if you are not hit.
A good example would be when I ran out of air and it was two or three of us vs 4 or 5 of them. I ran out of air and let my team mate to my immediate right know. Fortunately I was running remote so I just unhooked it and waved it around behind my bunker. My team mates quickly figured out I was out of air, but the other side did not know it. I managed to run up to their 40 and just played jack in the box while my team mates flanked them and we won.