I don't think Starmer is a right-wing plant. More likely to have been identified by Blair, Mandelson etc. although I don't believe they're left-wing in any traditional sense. The Labour party is now positioned where a more prominent Liberal party would ususally sit. Very much centre-right economically with very little in the way of left-wing social politcs. Starmer is the figurehead for that but the main body of Labour MPs have been pushing that way for some time.
On Gaza, I firmly believe that the Labour party has a duty to show solidarity with the civilians being bombarded. Where I tend to disgree with other posters on here is that I do think the UK has enough clout internationally to make a difference, and with a Labour government looming I don't see how anyone can argue that calling out genocide for what it is can ever be a bad political play.