Littlegolden the assets deletion would have to be tweaked. But currently if we stop deleting old assets, there's no way telling which ones are recent and which ones are extra old, and keeping them pile up for ever might not be advisable.
Maybe there's something that could be done at the webserver or proxy level to cache those files for multiple days, that way Flarum can remove them, but they will stay available to search engines. Doing this with Cloudflare should actually be relatively easy.