your two points are easily debunked by canon.
explain to me why when he is shooshpapping gamzee his text is lime green
why does terezi shoosh pap sollux in bright red? if it was relative to karkat then
a) only karkat would shoosh pap
b) all shoosh paps would be in bright green
and that’s another great point. karkat doesn’t even shoosh pap in lime green. it’s bright green. it doesn’t match lime green for trolls (or even cherubs).
have you considered the fact his this text is bright green because it was the only colour left that wasn’t already used in the panel? gamzee’s eyes are red so that clashes. karkat’s eyes are yellow and it’s hard to read. bright blue might be difficult against the purple for colour blind—plus it doesn’t look great either.
limebloods had a power that was a threat to the highbloods. we don’t know what it is. it is a fandom assumption it is pap shooping, spread by people who want karkat to be a limeblood.
why he is in between nepeta and sollux
because karkat is based on cancer, and cancer appears between gemini and leo. it has nothing to do with his blood colour. karkat does not appear on the hemospectrum whatsoever—he only appears between nepeta and sollux for the sake of the zodiac theme.
at no point has anywhere in the comic ever said that karkat’s position there means he was a limeblood. he always flashes bright red in that position. are you really assuming that hussie would be like ‘ok he’s in between sollux and nepeta for his zodiac sign. that’s enough. they don’t need any other hints or backstory or worldbuilding’. if so, are we even reading the same comic?
edit:
actually, something i’ve never expanded on before is the fact that karkat’s sign was created specifically for mutant bloods–after the signless. this means that it is a sign only mutant redbloods will take, from the whole ‘alphabet available’.
if it is not a sign available to limebloods, then they will not be able to take karkat’s 'place’. this would mean they would probably fall either side of karkat, in 'zodiac’ order.
hemospectrum and zodiac placing are two different things.
And EVERYTHING ELSE that supports this theory
there is nothing in canon that says limebloods mutated. no one ever suggests talks about karkat and limebloods. there is not a single indication in canon apart from this one strange ‘shoosh papping’ scene that seems to have been taken out of context.
what’s even more amusing, is the character that gave us all the information on limeblood trolls has been shrugged off from the limeblood route entirely by the fandom.
calliope didn’t tell us about limebloods because of karkat. she told us about limebloods because she believes she is the closest match to a troll limeblood. this is probably because she is, and the easiest way to narrate the backstory necessary for the explanation of her powers was just for calliope to talk about it because hussie does foreshadow and give hints and information. and all this foreshadowing is for calliope.
attention should be pulled away from karkat and placed on calliope—she is going to be the one who displays limeblood powers, not him.