Confirmation bias and the toupee fallacy both fall under the umbrella of selection bias, but they are not interchangeable, and the latter gets its own name because it's a specific type of selection bias. Confirmation bias would mean observing both normal cat-liking men and obsessive cat-liking men, but only paying attention to/including in your thesis that the latter category exists because you have a preconceived notion that all men who like cats are obsessive.

In the toupee fallacy, the first category is not noticed at all because that category provides no outward signs of its existence, the same way a toupee that's doing its job well is never noticed -- because the job of a toupee is specifically not to be noticed, hence the name of the fallacy.

You could argue that confirmation bias is at work here as well and I would agree with you.