In order to understand the issue about using the gear the shop sells, etc., it is important to understand the theory behind an agency like SSI requiring that instructors work for shops. (All of this was explained to me when I attended an SSI marketing workshop taught by its owner, Doug McNeese. This was before they were sold, but McNeese is still leading SSI.)
McNeese came to SSI from NASDS, which he owned when the two agencies merged. He then took over SSI and made NASDS philosophy SSI philosophy. The original name of NASDS, going back to the early 60s, was the National Association of Skin Diving Stores. It was a trade organization designed to help sporting goods stores sell scuba equipment. It came to the realization that the best way to sell scuba gear was teach scuba from the store, and it changed "stores" to "schools" in its name. According to its philosophy, the purpose of instruction is to sell gear, and the employee in the best position to sell that gear is the instructor. In the marketing workshop, McNeese advocated creating dive packages for people to purchase, with the most expensive one being the professional package. That package should be comprised of the combination that provides the best profit margin. He said all the instructors should be required to purchase (at a discount, of course) and to wear that gear package when they instruct, and they should be required to tell their students that they chose to wear that package because each item is the best there is, and as instructors they want nothing but the best. They are to say that even if in their personal diving they do not use a single one of those items, and they are to say that even if the items they do use in their personal diving are sold by the store. The key is to lower vendor charges for that specific set of gear, which will happen if you sell enough of them, so selling any of the other items on the store does not work in the long term best interests of the profit margin.
So if a shop has anything close to that philosophy, it is going to want to see all instructors wearing the gear they sell the most. They are not going to like to see some independent instructor coming in and implying that there are other good brands and models out there.
McNeese came to SSI from NASDS, which he owned when the two agencies merged. He then took over SSI and made NASDS philosophy SSI philosophy. The original name of NASDS, going back to the early 60s, was the National Association of Skin Diving Stores. It was a trade organization designed to help sporting goods stores sell scuba equipment. It came to the realization that the best way to sell scuba gear was teach scuba from the store, and it changed "stores" to "schools" in its name. According to its philosophy, the purpose of instruction is to sell gear, and the employee in the best position to sell that gear is the instructor. In the marketing workshop, McNeese advocated creating dive packages for people to purchase, with the most expensive one being the professional package. That package should be comprised of the combination that provides the best profit margin. He said all the instructors should be required to purchase (at a discount, of course) and to wear that gear package when they instruct, and they should be required to tell their students that they chose to wear that package because each item is the best there is, and as instructors they want nothing but the best. They are to say that even if in their personal diving they do not use a single one of those items, and they are to say that even if the items they do use in their personal diving are sold by the store. The key is to lower vendor charges for that specific set of gear, which will happen if you sell enough of them, so selling any of the other items on the store does not work in the long term best interests of the profit margin.
So if a shop has anything close to that philosophy, it is going to want to see all instructors wearing the gear they sell the most. They are not going to like to see some independent instructor coming in and implying that there are other good brands and models out there.