"Congressperson" is a gender neutral word. It is used in a professional environment as a non-sexist word. Compare "policeman" and "police officer", "stewardess" and "flight attendant".

Barclay, they were being snide, making fun of the congresswoman and about language changes that reflect a more equal status between men and women. Because congressMEN now have to refer to all congressPEOPLE and congressPEOPLE they made a pun and said that they were going to call congresswoman HoltzMAN ... congressperson Holtzperson instead to make fun of her and the fact that they have to change the way that they refer to their profession and themselves. It's a joke at the expense of women in general and at the expense of the congresswoman. It wasn't a very nice thing to say.