Might be a naive assumption from my side, but could it be that this group consists of mainly couples travelling together and thus have spread out as one couple per row in order to sit together given the 3-3-3 layout?

Could be that some TAs have special arrangements and can assign whichever seats they please too?

In your case, I think you can call TG to ask for row 31 seats to be unblocked if you want to take the chance that the bassinets are not going to be used.