Yes, I’m not a fan of the 404 solution. Seems like it could send bad signal to google and is also a pretty blunt-force way to achieve what I want. What I really want is the links not to be on the page, not for the links to be dead links.
To your question, the RSS feeds are "Excluded by 'noindex' tag" in search console. It’s unclear if this means google spent time fetching them and then excluding them or if they were excluded pre-fetch in which case the impact on crawl budget is likely less.