The thing is, if you do RBF (replace by fee), then you create a new transaction which has a new transaction id. Both nodes do not have any idea about the new transaction and will never accept it as their channel. Therfore the channel will never be "opened" and recognized by the nodes. So technicaly there is a 2of2 multisig which also can be used in a new transaction but both peers have to manually cooporate (sign the new transaction). And if you deal with an exchange like OKX thats not that easy.