I think he is just using his initiative.
A few years ago I advertised an Enduro frame on here with photos. Agreed a price with a guy who insisted he pick it up and would only pay cash on collection. Every time we agreed to meet he had an excuse as to why he couldn’t make it. Whilst browsing ebay to see what other frames were fetching I saw a frame for sale for a lot more than I was asking for, the photos were identical in every way to mine including the stuff on the garage walls, and advertised in the same location that he lived in. Contacted him and told him that due to him dragging his feet it was no longer for sale to him.
Sold some new Oakley shorts last year on here. Guy got a real bargain. They were back up in the classifieds the day after they were delivered using the same photo I had taken
I think this is happening a lot more but its hard to track everything.
Im not bothered if someone buys something of me and sells it on at a profit but using my photos to do it is taking the ****