You really want to get into this? Firstly, he is acting against the grain generally expected for agents - that's the first hint. Second, his outspoken nature obviously rubs key stakeholders the wrong way and causes an issue from a relationship standpoint - that's the second hint.
I also can't really fathom why you're asking me to "define destabilizing" but I suggest you pull up Raiola's timing of quotes regarding Pogba and our club in the past year and research for yourself.
And I disagree on him being crazy because, I genuinely think Raiola's influence has now gotten to the head. Saying things like "I don't give a feck if I never deal with Man Utd" is not a reflection of someone who is capable of creating a stable relationship with clubs, which is actually imperative in the agent domain. It's not because I'm a Man Utd supporter, but it's simple logic not to claim one is unaffected if they never deal with the biggest club in the world.
Regarding your point about legality, I never said what he did is "illegal". I said that the shit he does to achieve the end goal is not in the expected remit of being an agent, so it's not just "him doing his job".