The miner can drain this vault at ‘trigger withdrawal’ transaction by putting their input as first input, and the covenant-locked input as the second input. The output_0 will just be their input_0 amount going back to them (so input_0=output_0 condition will be satisfied) , while the covenant input_1 amount will be split between 546-sat dust amount at output_1 and the fee. Since the fee goes to the miner, they will be taking everything from the vault. Non-miner can just sabotage the vault by draining it to a random miner.
I currently don’t know the way how this can be fixed (edit: there are ways, see below).
By the way, 546 sat is the dust for non-segwit, AFAIR. For segwit, the amount calculated by IsDust() will be lower