They've really fumbled the bag with Heidi. She's the perfect All Stars comeback kid storyline, and has the talent, the personality, and now the improved quality of drag that would make for a highly satisfying winner amongst a cast of generally dimmer-wattage star power competitors (at least in comparison to previous years). Instead, they've seemingly given this role to LaLa (whom I do like, but just doesn't quite have the same impact as Heidi), are taking Kandy to the final as their main source of narrative, and are ultimately pushing Jimbo as their 'twist' of a winner this year ('we crowned a non-US contestant as an All Star - the doors this will open!').
I have real concerns that, upon smelling blood with Heidi providing them with a juicy story, they're going to double down and give her something of a villainous edit over the next two episodes, rather than a sympathetic one. I'm guessing Heidi's friction with Kandy will portray the latter in a good light, and the former in an envious one - they've already planted the seed in Untucked between Jimbo/Heidi, and Jaymes's talking head calling her 'jealous'.
Basically, I think they're doing something similar-ish with Heidi to what they did with Latrice in AS4. I'm not saying that Heidi is entirely without fault here if the above does come to pass, but I can also completely understand that she would spin out if she could see the writing on the wall.
I agree with your points that Heidi would’ve been a great come back kid kind of storyline and her drag has elevated somewhat since her season. She’s also so lovely and great television, which cannot be said for several in this cast.
However, additional tea on Reddit does suggest that’s not a straightforward situation between Heidi discussing eliminating Jimbo with Kandy. What is suspect to me is that the conversation between them happened ‘off camera’ (how convenient) so we won’t necessarily know the truth. Or at least, that’s what I took from what I read.