He mentions that many nodes already have a similar mechanism in place, but he raises concerns about whether the problem is truly resolved if the victim has to pay significantly higher fees than the prevailing mempool fees. He also mentions the possibility of burning a large percentage of the HTLC value.

It is unclear what specific problem or context Matt is referring to, as there is no further information provided in the email. However, based on his comments, it can be inferred that there is an ongoing issue related to fees and potentially losing value in the HTLC (Hashed Time Lock Contract) process.