I don't know if the White Council will actually try to whack Harry. The whole expulsion of Harry looks very bad and did not at all go the way Harry seems to think it did.
(1) Langtry forced the vote while McCoy and LTW were down for the count. It seems likely that Rashid was absent as well. He is often absent and we know the Outer Gates were under assault during the events of Battleground. These three are Harry's most consistent supporters. The pre-texts probably don't matter much to Rashid. Rashid is practically a part of Winter himself, given the fact that they guard the Gates. As for using lethal magic on the nominally human servants of the Fomor... that's garbage as well. They have a recognized exception for self-defense and Harry was in a war against those nominally human servants of the Fomor -- one that they started. Killing the enemy in war is not murder.
(2) Christos may also have been absent. We are told that he was very badly injured himself. Because Carlos doesn't mention him to Harry, we are meant to assume that Christos is anti-Harry, but we actually don't know that.
(2A) We don't know if Liberty attended either. She was at the battle, but I don't recall her status at the end.
(3) Given these 3 - 4, maybe even 5 absences, a "unanimous" vote to expel Harry would be easily achieve. We know of the way the Senior Council functions and specifically that Langtry held the proxies of every absent member. Mai is also in his pocket and very anti-Harry.
(4) The vote and meeting was an absolute mess. We know this at least because Carlos is mentioned as having been "shouting." Even if one did not like Harry, and even wanted him out, one could still object to the obvious injustice of holding the meeting without McCoy, LTW and Rashid to speak on behalf of Harry, to say nothing of Harry himself.
(5) The outcome reeks of Langtry's attempts to "compromise." Harry is out supposedly because he's a black wizard, but then they suspend the sentence? Then task the one man in the council that you can be sure won't kill Harry with the job of cleaning up, if needed. Give me a break.
In the end, I think it more likely that Langtry believes this maneuver will give him some much needed leverage over Harry: Do this/Don't do that and we'll reconsider.