My understanding is that if you want to move between bitcoins L1 and drivechains, miners have to sign off on that. Similar to how miners currently have to choose to include your transaction in a block...
@21_21_21 inclusion is a per block choice, so one miner refusing you just means the next block takes it. a bip300 withdrawal needs a hashrate majority acking the same bundle across months, and a minority cannot route around that.