Having a team member test positive is definitely a worst-case scenario. I believe the responsible thing to do would be for the rest of the team to stay out of the bowling center for 14 days, and then come back when they are certain they are clear. Allowing them to make up the 2 missed sessions seems reasonable as long as it is done in a defined amount of time.
It also isn't just their teammates that need to worry about it. It would be whoever was on a pair with them prior to their positive diagnosis. That is a potential exposure that might also need to stay away for 14 days. Hard to really say, though.
Leagues here are going full-tilt this Fall. Full nightly schedules, no empty lanes between bowlers, masks optional, full food service, drinks, etc. It is kind of scary, and in some cases in total opposition of state guidelines, but the bowling centers are doing their thing and relying predominantly on the bowlers to be the responsible parties and avoid risky behaviors.
I have been bowling on leagues now for the past 6 weeks, and wear a mask and stay away from others. So far, so good. We have made it longer without a positive case being reported by a bowler than I thought we would.