It's not so easy. People can mostly do what they like behind the VPN, including setting up Tor exits. I'm regularly speaking against doing so because the implications for other AirVPN users are greater than the gain for the Tor community.
Also, nothing says that a "good" server will not turn bad at some point. Plus, it's not like a subset of servers are blocked everywhere and another is not; if that was the case, all people would always use good ones. No, it depends on the service you want to access. Some block Tor exits forever, others only bad IPs for some time only.