I don't think it's hard to understand. Reloading battles would cause statistical bias just like reloading a CC check. And it's difficult to avoid unless the player examine the statistical distribution carefully, or save far apart. He doesn't necessarily cause it intentionally.
The argument is completely illogical for the point you are trying to convey. I already explained why.
Savescumming is not restricted to games with RNG. Not only that, but it is also player side issue, not a game issue.
Portraying it as a factor against the type of RNG being discussed is dishonest, to be light about it.
Note that this is not a critic to what you are pointing out about savescumming creating bias, that much is correct, but it doesn't support what you're trying to say it does, at all.