Remember what is actually suspect about the Space Wolves though. It isn't that they have a variant TO; it's that their great companies are self-sufficient expeditionary units (traditional battle companies are not). Just like the Black Templars' massive fleet, that raises the spectre of the Heresy - marines gone wild. They also have such a serious flaw in their geneseed that they occasionally become werewolves, which are a bit hard to rationalize as a variant of homo sapiens. And then their chapter master has the balls to threaten the entire Administratum. Even if he pretty clearly didn't mean it, that is a bit different from the usual run-of-the-mill "make me" when somebody tries to tell the chapter what to do.
It isn't variance from the codex that makes space marines suspect to the Imperium at large. It's acting like you are a threat, or planning to be a threat, or might accidentally become a threat, to the Imperium.