I don't think it's relevant to make topics change their icon to the account picture of who posted last. Would be easier to skim through topics if the picture of the one who created the topic appeared instead. Just sayin'...
I can hide the icons but I can't display the original author's icon.
They're hidden now !
I've noticed today that when doing a search, the results contain the original author's icon (instead of the one of the last poster!).
(I was preparing to write back that the icons are not completely hidden ).