Is this issue here that the party in control of TxB is paying 1,780 sats over the “pure burn” ephemeral anchor spend to evict TxC rather than a separate transaction paying > 10,000 sats per rule #3 (thereby saving money and incentivizing inflating the anchor)?
If we start with 0-value outputs but still want to keep the commitment transaction 0-fee, couldn’t we add an anyone-can-spend output that’s timelocked far in the future (and hence won’t interfere with anything in the mempool)?