DDoS is not the only problem the internet faces. It might just be that someone behind AirVPN is running script kiddie stuff on an automated basis. We can't know, because security companies exist so that people not knowing much about malware can buy in such expertise. In such a situation it's difficult to verify claims such a company makes. Wordfence blocked access, but on what basis? Ask. That's when they will say "we can't tell because otherwise the bad guys will know and try to go around".