It's a super cool idea but honestly, thinking back to the many times I copied Luna or Mantis for their defensive Ults, I think copies autohealing could be a little bit too much. And as far as I've checked, his healing wasn't nerfed as hard as his damage was, so personally I'd take a projectile speed buff rather than a buff in raw number.
Not to mention that Loki did not receive the season bonus this time, making his healing seem weaker in comparison to the other characters that received it (which was everyone except for him and Rocket, I think??). If anything, I'd rather the devs removed all the season bonuses and tweaked the global healing for all characters, if necessary.