This information is incorrect.
You are right. The genetic component of male pattern baldness is a little more complicated than that. Actually, using my family as an example confirms this. While my mom's dad was bald, so was my dad's dad. Guess I didn't stand a chance. In the example of my son who at 45 has all his hair, his mom's (my wife's) dad had a full head of hair when he died in his mid 80's. This would lend credence to fathers not passing this gene to their son's. But, it's not that simple, is it?
Much research went into the genetic component of male pattern baldness, or androgenetic alopecia (AGA). Research indicates that susceptibility to premature male pattern baldness is largely the cause of sex-influenced inheritance (because males can pass on the trait to their sons which would be impossible if it were x-linked). Other genes that are not sex linked are also involved.