Your claim that AUS feels unthreatened by Murali’s average of “70” reveals the problem to be more serious than a warne rivalry. Its an attack on Australia's premier icon, Bradman, the guy who was famous for being not quite good enough to average 100. Your average of 70 includes the ICC farce. In actual test cricket, Murali manages to average well over 100, exposing the mediocre average of Bradman and the inadequacy of Australian cricket in general.I don’t know if it’s either of those things specifically. Hair did exactly what was right. I don’t know if it’s the Warne rivalry either tbh, because when he toured here we’d have been happy to have Murali bowl from both ends - he averaged 70.
It may be that a lot of people thinks it’s over the odds for a bloke to be called under the rules then have those rules changed for him. It’s a very SC reaction to something - when something goes against you, spit the dummy and threaten to go home until you get your way. See also - Pakistan at Lord’s, SL in Adelaide vs England, India any time they don’t like an lbw decision.
Australians have been willing to do anything to discredit murali to avoid this cold truth that they have failed as a nation.
More seriously, its easy enough to justify a position for or against Murali. Neither position is surprising. But the split in support is surprising. A heavy proportion of Aussies take issue and a heavy proportion of every other country supports him. The difference in AUS perspective cant come from general criticisms as you are suggesting. Aus differs in view due to some circumstance or perspective. Warne rivalry doesn't seem sufficient reason. Perhaps the circumstances around Hair. You say it was the correct call. I cant remember if a general perspective existed outside Aus. But Hairs idea that home advantage should be extended to umpiring and general dislikability had not made him popular. Widespread condemnation of Hairs actions on principle wouldn't surprise me. Did this maybe happen, resulting in an Aus media reaction in his defence against Murali, causing a rift between Aus and the rest of the world? This is a huge work of fiction on my behalf, but something along these lines must have occured