Small quibble: at least according to her twitter account linked from the sidebar of the linked post, the author of the linked post ("Eevee a.k.a. Evelyn Woods") goes by "she/her"
Peppermint Patty´s best frient, Marcie, tends to eccentrically call her "sir", which may be due to Marcie´s bad eyesight and Patty´s slightly tomboyish behaviours. Patty at first is hugely annoyed by that, but eventually starts to accept - or better, less obviously discourages - that behaviour.
I don't think Peppermint Patty is disrespectful personally.