Blondu may be playing a double act, but I doubt it, he was part of starting the momentum AGAINST Sab near the deadline, before it was even probable lynch to get her. Maybe it was a "safe" G thing to do, vote for another G who isnt likely to get lynched, to add confusion. And maybe he turned out to be unlucky Ze said he is the detective and trapped Sabet, making sure Blondu has to be part in lynching her. But it might be overcomplicating it to think that. Maybe Blondu is simply a C who for some reason found Sabet suspicious and voted for her.
The only thing off I find about him is how he coud be so sure Ze was civilian before Ze said anything about being D? He was rather adamant. Mainly Gs know peoples general roles (as in C or not, not special roles), so that may be a possibility. But IMO it mainly just looks like him voting for someone who suspects and that one turning out to be a G, not a G bluff or so. Sometimes the more simple things is the reality.
And btw, find Fred and Ahmed bit convenient so far, Phrozen going for Blondu seems bit random, not that he is wrong necessarily, but dont see how he is more likely then the others. In Particular Fred.