What would prevent this scheme?

If you were a validator, is there anything that would prevent you from waiting until you have been selected to propose a block, then submitting a large transaction so that it is visible to MEV bots. The MEV bots get into a bidding war attempting to sandwich your trade, you pick up their transactions and take the large tip but then don't include the tx you submitted when you broadcast the block to the network. In this way you cheat the MEV bots out of a large tip.