Yep, I've alluded to it several times that Lowe might have fractured his friendship with MacT based on events this season.
Interesting to note that this is not the first time Lowe has done this. He did it with Tambellini ---> MacT as well.
It's pretty clear throughout this, that Lowe has been dispossessed of his power to affect the situation almost as much as Mactavish has been.
Lowe made the decision on Tambo, I don't think he had any say in the Chia hiring. He likely even thought that he was just helping recruit Chia for his own position, and Nicholson made the call to pull the trigger when Chia demanded GM and POHO titles.