I don’t see it as a coup. I see it more in the way of a group of like minded MPs forming a majority, which is how parliament works. A coup is more akin to seizing power either by actual force or violence, or a threat of those things.
Even the most devout Brexiteer must now admit that the things which the Brexit campaign was fought on, no longer exist. Every main point used to sell Brexit has either turned out to be untrue, impossible to achieve or has been abandoned.
Now, in the absence of any claimed or stated advantages to leaving the EU whatsoever, an absolute void of ideas or ambition, it is only right that someone takes Brexit by the neck and puts it out of harms way. That’s not a coup, it’s an act of euthanasia.