This doesn't make things necessarily more sour. Firstly, given the evidence in the post, it sounds like a BS claim (although only a lawyer would know). Things are already sour. That being said, reaching an amicable arrangement via legal proxy doesn't make the situation sour at all. Getting lawyers involved is not an aggressive action - they are the subject matter experts. Just like you wouldn't have a software architect dealing with relations, you don't put a founder in charge of legalities.