Should I report a guy who did the following?:

Hello!

I am a Rocket League trader and I do cross game trading. I warn my customers the first second they add me that they will have to go first.

So a trader contacted me and was being disrespectful within the very first minute. I think he knew that he wouldn't trade with me and he just wanted to waste my time and accuse me of being a scammer.

I tried to be as respectful as possible, but his toxic behaviour and broken English really annoyed me. I was chatting with him on my smartphone. I asked him one more time if he will want to make the trade and he told me YES.

I went to my PC and booted it up. When I turned on my PC and opened the game (Rocket League), I invited him to trade. He showed me that he has the keys and ordered me to give him the keys. I told him that he has to go first. He got angry and started calling me a scammer. I defended myself, but he still attacked me. He claimed that I am a scammer and I delete my Steam comments. He also said that not having a nice looming bio also makes me a scammer.

He really annoyed me so I decided to write a -rep on his Steam profile. This is what I wrote: -rep not willing to go first after confirming that he will do just that. Wasting time, false scam accuses.

A few moments later, he posted the EXACT SAME thing on my profile. He said that he is doing this to prove that I delete comments and I am a scammer.

Should I report this person on SteamRep?

Edit: He also said that I am banned on a list of Rocket League Scammers, even though I never scammed anyone.

No, you can only report actual scams or scam attempts here

Just ignore and block him.
He noticed you are not going first so he tries to get under your skin in the hopes you will give in. Don't!
Any person who is really looking to trade, will just say "no thanks" and move on.