I don't see why Shallam should expect to be able to break the treaty just because Tylin attacks them. The treaty is very black and white in terms of what is and isn't allowed. Declaring personal war isn't even mentioned in it. The treaty specifically disallows convocation, and does not give any provision for exception. Shallam may have signed a treaty they don't like, but that doesn't absolve them of guilt if they break it.

Penned by my hand on the 7th of Lupar, in the year 236 AF.