TFA seems to offer a solution for that problem with "Experience uncompromising privacy with AzireVPN's Blind Operator! Your port stays confidential as we don't store or log assigned ports in any database. Thanks to our secure Blind Operator backend, your assigned port remains private."
Ultimately you have to take their word that it works as well as described.
Port forwarding doesn't assist in deanonymization. Ultimately you either trust your VPN or you don't.
But fingerprinting isn't deanonymization anyways. And this is stretching the idea of "fingerprinting" in the first place -- a single port number provides the same amount of information as an IP address. With a VPN you can rotate both as often or as little as you like.
Compared with what other options?
Mullvad does not support port forwarding. You can try to defend it all you want, but if someone needs port forwarding and your alternative does not support port forwarding then you need to find another alternative or your point is moot.
This results in raids leaving empty-handed: https://news.ycombinator.com/item?id=35638917
This is in contrast to the flocks of VPN providers whose retention-related claims were either complete horseshit or not well-implemented.