First, I'd just like to clarify something I said, because I don't think I conveyed it properly:
When I said you were strawmanning, I mean you were making up a baseless caricature of the staff team. May have used the term improperly.
No, we're not going to make a global rule against spawncamping. Many maps are structured very differently. Some, especially Achivement/Idle maps, are structured to encourage spawncamping and many use it for spawncamping to farm kills or whatever. It would be extremely counterproductive, therefore, to enforce against spawncamping there.
Regarding stock maps specifically, well they are apart of normal TF2 gameplay. Spawncamping is annoying, but so are dominations, well-placed Mini-Sentries, a lot of things. We are not going to disallow something just because it commonly annoys players, else we would be disallowing a lot of integral things to TF2 such as players being F2P or squeakers.
Furthermore, there are many ways that, especially on 2Fort, you can counter spawncamping. If your team is getting spawncamped, it's honestly your guy's fault for allowing them to get that far into your base and spawncamp you in the first place.
Team Fortress 2 is, as the name implies, and team-based shooter. You have to cooperate with others to succeed. If your team is not coordinating well and the enemy team is, well then there's not much I can tell you. We're not going to make the rules act as a crutch for poor performance.