Also true.

But it looks to me like there's a decent number amongst the other nine who know what grenades are and don't want them to get thrown by the tenth.

The power dynamics here could be just about anything; I don't know how to begin to forecast the risk distribution, but I definitely agree that what you fear is plausible.

it's possible that the other 9 would keep the 10th under control, but if you look at the direction the US has taken, when two billionaires took over and declared inclusion verboten, the others rolled over and updated their policies to fall in line.