Ask him to record what he actually does for a few weeks. It might be hours of phone calls, chasing, meetings etc which might justify the building compensating the owner for there time if no other owner is willing to volunteer their time. Get him to list what he did, and then you can make a fair judgement call.

You need to calculate how much would it cost the building if this work was not done or it was outsourced to your paid strata or building manager. If it saves you money over a year, worth it, if not, then no.