Sometimes a single post is a hit and run. Other times new posters may simply not understand there's something of an expectation they will come back and reply to comments or otherwise participate on the board, or that people may look upon single posts like that suspiciously.
There are definitely legitimate cases of folks joining to post a single thing. This could be one of those, or it could be a dirty trick by a competitor. Pity there's no way to tell. I can say that I've joined other forums on occasion with the intent of only making a single post and never went back. For example I found a dive watch about a year ago and posted on every dive related forum I could find. Most of them I asked for a PM and set the forum up to email me if I got one.
Honestly it hadn't occurred to me that this could be a fake report. Pity that nobody has corroborated (or denied in the case of the op) the report. However this is at least the second post this year I've seen from someone on this forum mentioning the "agressor fleet" using the "not our fleet" copout. I'd think if it were a fake smear campaign a response from agressor to that effect might be appropriate. Hard to believe they would not know about this message. The post is in THEIR section of scubaboard and it has nearly 2,000 views. On the other hand they may just say "not our forum" and be done with it...