No. It is not an ad.
The person posting is only expressing his feelings about a vendor who has done well by him.
He receives no compensation for doing so and there is nothing of value changing hands because of it.
What has occurred here is a thing called word of mouth. That happens when a vendor does a good job of serving their customers.
If this bothers you and you are not somehow connected with another vendor, then I don’t see your gripe.
If you are connected, and it bothers you then buck it up or step it up.
As you are not the person who wrote that post, you don't know if it was an ad or not -- if he's affiliated with them or not. I also misspoke because I should have said, "To me, it reads like an ad." I can't possibly know if it was or not. He can speak for himself. Of course it's fine to recommend a vendor but the OP is looking for recommendations of basses. He's presumably researching his options before dealing with a salesman, which is a wise decision. The advice amounts to "go to my salesman" which isn't useful when the guy is asking what options are out there.