"It seems as if the author claims that for the vast majority of my 60+ years, “tranny” was not even considered a slur to transexuals themselves. It was used as a term of self-identification until relatively recently."
Then you probably think the N word isn't a slur?
"Yet, Trump supporters are not protected from any speech"
Neither are Democrats. So what?
"Yet, you are allowed to get away with a comment intentionally intended to denigrate an entire group of people as pussies"
So are conservatives who call liberals names
"I believe that you used the term “pussies” in an deliberate attempt to be offensive to every single Trump supporter. Yet, you think this is perfectly OK"
Like you use the t word to be offensive to every single trans person?
"Who says it’s a slur? Who gets to decide?"
Trans people say it's a slur. As well as many others. If a certain group of people find the word offensive you don't get to tell them it's not offensive. You don't get to determine what other people are or are not allowed to find offensive.
Go call a black person the N-word and tell them that they're not allowed to get offended because you personally don't find it offensive.
"Tranny is not a slur, and never has been. It’s just an abbreviation."
Slurs for numerous groups are abbreviations.