This is assumption based on casual empirical observation. To see whetherr it is true in reality you would compare the ratio of - Lefties dismissed by Murali to Righties dismissed by Murali - to the ratio of - Total Lefties to Total Righties - (who played during Murali's era), and see which is greater.
For you to be correct; LDM/RDM > TL/TR by a significant degree.
Or something like that.
Point being that Warne was brilliant no matter whether the batsman was left handed or not.
Given that virtually everyone is putting names like Hobbs, Hutton, etc. forward based on 2nd hand knowledge of people passing judgements on these guys based on their casual empirical observation, it is more than fair to use the same benchmark on Warne/Murali and others who I have seen personally and is thus, a 1st hand empirical observation.
Also, your methodology is flawed. The ratio of lefties to righties dismissed is inherently dependent on the number of lefties and righties in the lineup. For eg, if you play against a team of ten righties and one leftie, unless you only take just one wicket (of the leftie), any 5 wicket haul or more will inherently skew the figure in favour of the righties ratio. The opposite also applies.
In Warne's time, the team with the most # of lefties playing test cricket were West Indies and England. Warne has far more tests against them, so i expect his lefties to righties ratio to be greater than Murali's, who played significantly less against them.
Warne was a brilliant bowler (except against India, against whom Murali was far more threatening) but he was distinctly better against righties than lefties.
Lara, Ganguly, for example utterly dominated Warne. Made him look like Tahir more often than not. Against Murali, Lara hung around dourly ( even in the series Lara scored 600+ runs, he hung on for dear life against Murali and smashed everyone else) while Ganguly was distinctly uncomfortable against Murali.
To any neutral observer (and I am, since I am neither Aussie, nor Lankan) who've seen them, it is patently obvious that Murali was much, much better against lefties than Righties compared to Warne.
This is not just because Murali's stock ball went away from the lefties/Warne's stock ball came into them and that Murali was more accurate than Warne, its also because Murali's doosra turned prodigiously the other way, which meant Lefties couldnt just leave anything pitching on leg or middle from Murali to carry past offstump, while Warne never had a good googly (it was well disguised but it held its line, didnt turn the other way much) and lefties could afford to leave anything pitching on leg from Warne due to it.
