No problem at all ... I think ... should be a 3-5 lines in shell code ... 
(I mean the LAA-Bit detection)
The risks of false positives / false negatives is quite high ... a VPN is always the better approach.
I’ve tested this and there is an extremely low chance of false positives and false negatives. The logic itself is sound. If you want you can test it before implementing it. That might be good idea to put the logic to the test before implementing a lighter weight solution like bash.
Well you should do more testing ...
Virtual BSSIDs in multi-SSID setups (very common in business/hotel APs), some mesh implementations, and a few consumer brands legitimately use LAA bits on secondary radios.
Travelmate's use case is roaming, where you usually have no trusted baseline anyway. Without a pinned BSSID, the surrounding evil-twin logic has nothing to compare against, and the LAA bit alone tells you essentially nothing — plenty of legitimate APs in the wild have it set.
Anyway I'll add that with the next update and by default this feature will be truned off - the LAA check is a nice-to-have telemetry.
Evil twin detection has been added to latest travelmate in master and 25.12. branch, for reference: