Health: It is fair to compare reform and conservatives to the karaites that the Rambam had. This requires a bit further looking into. What does the Rambam do with Kol Yisrael Areivim and Lo sa’amod Al Dam Re’acha here? This is an interesting thing to look into.
On a side note, even if there is no Chiyuv to be Mekarev that doesn’t mean that anyone, ever, has a right to push away someone who wants to come closer to Yiddishkeit.