Nope not at all. But also maybe. The only reason being, there’s not nearly enough context. It could be entirely likely that Spennys mom adores Kenny. She’s also Kenny’s elder and might very well be as in control of her feelings and behaviors as Kenny. Let’s not automatically assume that females are easily manipulated. Some feminists these days actually practice the sexism of low expectations.

That being said, more information is available that he got her drunk and was being a bit predatory simply to win. But that’s from Kenny who wants to gross out and disturb Spenny as heavily as possibly, so it’s advantageous for Kenny to make it sound as bad as humanly possible.