It's much the same, aiui. A rogue relay could just ... not honor your edits or deletions, but people would pretty quickly stop publishing to it if word got out. Much like a rogue Mastodon instance that won't honor deletion requests being defederated.
Discussion
Yes, that is probably correct. Like Google cache or internet archive is going to keep your public post forever.
I really do want to be able to delete my posts after a few weeks. Data hygiene. I use this auto delete option wherever I have one.