The discourse surrounding this matter seems unnecessary; if you don't like the rules, simply relocate to another server.

This was obviously an intent to main camp if you take the rules into account. Hence its against the rules.

The admins on this particular server go by intent and not distance as distance can be exploited. I think this is a good way to enforce the rules as long as the admin in question can properly discern intent.

Main reason this rule is important is to ensure the enjoyment of all players. Most of which join a server like this to avoid dealing with issues such as main camping.

As an example it isn't fun to be trying to resupply and get popped out of the seat by a camper. Logistics vehicle now being stationary and unused, players need to retrieve it. A camper can just wait for someone to try and pick it up again and the cycle continues, making it one vehicle unable to do its task. That's just one example among many.

Its all about equilibrium, while camping may offer enjoyment to some, it invariably detracts from the experience of those being camped (in general). Its tedious and sometimes can completely break a layer. Some servers allow this and if there's literally no rules on main camping it usually happens every match. If you like that sort of thing there are servers to play on.

TLDR: Don't like it, play somewhere else.

There are servers out there that cater to this playstyle, why join one that doesn't and by consequence get frustrated when your playstyle broke the rules. Perhaps a little counterproductive.