I'm going to put the military issue in simple terms. If we are allied with TNP, then in a UIAF raid TNP chooses between allies (in conditions where the alliances do not require its support). If we end our alliance, then it potentially has only one ally involved: Albion. Our alliance gives TNP more room to choose to oppose a UIAF raid. I think this is in our interest.
It also gives them plenty of room to choose to go ahead and support it, in that our treaty draft makes clear that being on opposite sides of a military conflict in a third party region isn't a problem for the status of the treaty.
Albion is not likely to be the only TNP ally that is a factor, in any case. Combine Albion and Europeia -- which frequently happens -- and the scenario is that TNP has two allies supporting the raid, one ally opposing it, and no obligation to the latter not to get involved. What do you think TNP is honestly going to do in that situation? Why would it not get involved when we are saying, through this treaty: "Go ahead. We don't mind. Not a problem." -- and how appropriate is it for us to even be saying that? Are we regional sovereigntist, or not?