well i'm glad the name is less unpronouncable now, that's something at least.
it's still dead though, the fact that somebody renamed it or whatever is not going to change anything, push for rss feeds is a niche of a niche of a niche of a thing nobody cares about.
when i did initial implementation we didn't have the robust plugin system tt-rss has now, nowadays i think core code for this is unnecessary, especially if people pushing (sic) it decided to implement non-backwards compatible change on top.
if someone is really interested in webpushing they are free to implement support as a plugin. if there's any hooks missing i'll add whatever needed, although i think everything should be in place already.
personally i haven't seen any feeds supporting pubsubwhatitsface for years now and honestly idgaf, it's dead code.