To you final question the answer is "just wait a while" because 6 confirmations is when that feasibility becomes so highly unlikely that it's not worth worrying over.
Discussion
Sort of unrelated, but do you happen to know why Liquid peg ins take 102 confirmations? Are they trying to get the probability of a reorg to ~0%?
I think this actually could be related, but may piggyback the Bitcoin coinbase output that cant be spent for 100 confirmations. For example if a miner pegged into Liquid using their coinbase then that address (the peg in) couldnt be spent for 100 more blocks. Does make me curious if theres another reason