Trying to buy a Road bike Felt odd

Was looking to upgrade my Cafe 7 Felt with accessories like a basket or rear rack but came to this add on OfferUp for a Felt Road Bike. Thought maybe I should just get into a faster bike. I didn’t expect how this conversation escalated to this.

Maybe I was rude at the beginning. You be the judge. If you were selling you $2000 Felt bike.

Me: what’s the serial number? Are you the original owner and where did you buy this bike from?
10 min later
Seller: decided to keep it its so sweet
Seller: I have sold Felt TK3 54CM bike. Thank you.

Well that brought such suspicions reaction to my questions.
I then asked.

Me: Are you the original owner? Should I turn you to the police?
Seller: What?
Seller: do you see my 37 all 5 star?

Me: it is a sweet bike and I contacted you regarding it and al of a sudden you want to keep it and it’s sold? Upon the questions that I have asked you?

Seller: Correct
Seller: that doesn’t mean it’s stolen

Me: you have proof that you are the original owner?

Seller: Call me
( at this point I didn’t know what the seller is asking me because I have not asked for his/her number)

Me: for what?

Seller: to speak about this.

Then the seller began to bombard me with a lot of messages regarding how he was mistreated on this app and how dare I request serial numbers and rightful ownership documentation.

I was just trying to buy an accessory for my cafe 7 not to get involved with this.

I did jump into conclusions that this bike might have been stolen but the sellers reaction has told me other wise. Have I done wrong? Please help me understand his reaction so I do not offend people.

Hello I’m sorry if this is not relevant.
I want to look up a bike to inform myself if it is safe and ok to purchase and also what specs I can find even the model of this bike. How do I go about this?
Call me if u want 253.455.4548
Time is critical pls