Religious fundamentalists tend to be less corrupt than whatever your baseline for politicians and rulers is because within their in-groups they're scoring each other based on those ideals. Not to say they won't loot like every other ruling class does, but they're not gonna behave like Saddam (most obvious local comparison point for this subject IMO) and just light money on fire for their own flamboyant luxury.
Their values may be garbage, but that's tangential.
Talibans are the obvious counter-example. No, the reason they might be less corrupt than the average dictator in the area is that they seem to have a plan, and until it is implemented, we can expect the leaders to behave.
Also culturally, Syrian are very close to Turks and benefitted a lot from ottoman administration and Sunni legalism, which is a big reason why I believe it is possible for them to have a (mostly) secular government. Sadly I think it is likely they will implement a dual government like Iran had, a theocracy with a democratically elected secular government. Which are more resilient, but bad news overall (still better than Assad regime tbh).
> Religious fundamentalists tend to be less corrupt than whatever your baseline for politicians and rulers
Citation and some kind of proof needed here. It is very dubious proposition.
> because within their in-groups they're scoring each other based on those ideals
Their ideals dont tend to be "transparency, anti-corruption and fairness". Those three tend to be fairly low on the list of ideals they score each other on. For example, Iranian regime is considered very corrupt.
> they're not gonna behave like Saddam and just light money on fire for their own flamboyant luxury.
That is just a matter of aesthetics. Not a measure of coruption.
Their values may be garbage, but that's tangential.