It's possible to think of this as an opportunity for our servers.
We could gain a lot of traffic while this game is still in its developmental stages.
The main issue I have here is the compatibility, and the accessibility of the servers. People need to join from a separate/modded client I believe. Also, the compatibility of TF2SS's plugins and/or maps. Unsure if any tweaking would be required.
Nevertheless, it is still a decent idea. - Not bad.
You do understand that this mod has been practically dead for months now, right? I have no idea what the development team is doing, but I'm sure they've been behind for quite a while. In addition, the community barely exists. Not only would you have to work for functionality on these servers but you would also have to work to practically build a community for the game. Would you or anyone else even want the same functionality and maps SwapShop applies to the TF2 servers?
To be honest, I'm not all that deep into the community. I've never even played the mod myself. I've seen some talk and gameplay but that's pretty much it.
In regards to how tf2ss would work on the servers, well, shop has always been an integral part of the community. It's custom for players to be able to buy credits and use them. In-game currency. I couldn't imagine that feature being excluded, especially one that was made specifically for tf2ss.
However, I could live without it if need be. Who knows? It may work regardless. I don't code plugins, so that's not my expertise.