In the beginning of Parashat Balak, Rashi writes:
If you ask, “Why did God bestow His Shechinah on a wicked gentile?” [The answer is] so the nations should not have an excuse to say, “Had we had prophets we would have repented.” So He assigned them prophets, but they breached the [morally] accepted barrier, for at first they had refrained from immorality, but [Bil'am] advised them to offer themselves freely for prostitution." (Bamidbar 22:5)
Nevertheless, the other nations could rebut saying, "Bil'am was a wicked man. If you had bestowed prophecy to a righteous gentile, we would have repented."
Why is this not a good counter claim?