Newsblur reports “Not an RSS feed (553)”, but it appears to be a JSON feed. I’ve compared it to other JSON feeds that work just fine. The only immediate difference I see is the bad feed is escaping / as \/, whereas working feeds do not. Wasn’t sure if that was causing issues with your parser.
https://www.scottboms.com/feed
https://www.scottboms.com/ethos/feed/