If silence means everyone agrees MTP isn’t secure, isn’t supported by PoW, and shouldn’t be used or recommended for any purpose that makes those assumptions, here’s an alternative that doesn’t require a change to bitcoin. Instead of using MTP, use the highest timestamp out of the prior 11 blocks and the current timestamp (or more simply, the highest timestamp seen). This would be at most 2 hours in future which is consistent with timestamping (whereas being in the past isn’t). This has PoW support and is enforcing monotonicity. The highest timestamp seen would have better PoW support if the DAA changed every block which would increase the cost of miners delaying timestamps during the 2 week adjustment period.
Miners should enforce monotonicity even if it’s not a requirement.
It’s not a big problem in this sense: if timestamps are observed to monotonically increase, the MTP and the timestamps are valid and have PoW support. The degree to which they don’t have PoW support is limited by how far out of sequence they get. If it’s a problems, it can be seen and the highest timestamp seen can be used. The problem is if code, script, apps, or legal contracts depend on MTP or current timestamps as accurate.