I would argue that in many cases the concept behind soft deletion is to make deletion permanent.
Hard deletes retain no memory of what you wanted to be gone, so any malfunctioning sync process will continuously recreate the deleted record soon after it's deleted. Soft deletes are often the only way to make sure deleted records don't reappear.
Null is more ambiguous than an explicit conflict. If there is literally no record, even of the delete action then there's no timestamp for last write wins.
Assuming you're using a modern database, replication is done with paxos/raft and they are formally proven to not allow this to happen as both edits/deletions are both just entries in distributed event log.
