Speaking of Hoplophobia

Below is an example of when neurotic hoplophobes call in the boys in blue rescue them from scary gun imagery that brings on spasms of involuntary enuresis:

I was watching a video review of a Ruger Mini-14 on my laptop while riding home from work on a New Jersey Transit bus the other night. I sat quietly against the wall of the bus for a solid 40 minutes traveling from NYC to New Jersey, with my headphones on, minding my own business, anxious to get home since I needed to pick up medication for my wife. Every now and then I noticed the guy next to me was acting squirrely. He was on his phone a lot while drinking his beer in a brown bag but I didn’t think anything of it. The bus finally got off the Turnpike and arrived at its first stop . . .

Suddenly I see a police officer coming to the back of the bus. I take off my headphones wondering why a police officer would be on the bus and what could be happening when he turns to me and asks me what I was watching. Being completely caught off-guard and with a huge lump in my throat, I told the officer I was watching a review video about a rifle. He then asked me to get off the bus and come with him.

Everyone on the bus was looking at me like a convicted felon and a monster. I got my coat and bag and left with the cop. Once outside, we were met by three more officers as my bus pulled away. They then began to ask me, again, what I was watching. It was reported I watching “offensive” material. They wanted to know what was on the video, etc.

I proceed to explain that I was simply watching a rifle review video about the Ruger Mini-14. They then ask me if there was any “German eagles” in the video or beheadings. I was then truly perplexed and started to get really worried. There are no beheadings or even scenes of violence and there were no “red flags” or “German eagles” anywhere to be seen.

It then dawned on me that the Ruger logo had appeared in the video, so I explained that to the officer. Thankfully he was aware of what the logo looked like. After showing them some of the video and explaining what I was watching, they realized I wasn’t doing anything illegal . . . though I didn’t know that watching “offensive” or “political” material while on public transportation is a crime. [emphasis mine]

It's not a crime...yet.  Reading this, I'm wondering just what legal authority said transit officer had to detain this law-abiding citizen.  Where was the crime and / or probable cause here, other than the obvious felony inherent in causing incontinent bowel function in ignorant urban blue-staters?*

The legally proper thing for this citizen to to in this situation would be to inquire of these officers: "of what crime am I under suspicion of committing?" and "Am I free to go?".  Yet utterances such these days that are legally, Constitutionally, and 4th Amendment-proper carry with them a certain amount of legal and physical risk.

* But I repeat myself