What can we do with a player who camps in a table top game?
There are already quite a few ways you could deal with this, some based in the rules, and some beyond the rules:

As long as one of your units can see the hidden unit, it stops being hidden

From the rulebook (page 11):


  If an enemy moves so that he can see the hidden warrior, the model is no longer hidden and the counter is removed.


It may be worth sacrificing a fast-moving but weak unit to remove the hidden counters from the opponent's units, thus allowing the rest of your warband to use ranged weapons against them, or charge them first.

Units within a number of inches equal to your initiative are automatically spotted

From the rulebook (page 11):


  Enemy warriors will always see, hear or otherwise detect hidden foes within their Initiative value in inches. So a warrior whose Initiative value is 3 will automatically spot all hidden enemies within 3"


So even if you can't get into direct line of sight, again sacrificing a unit may reveal some or all of the enemy warband.

If terrain permits, you may also be able to move one of your own units with a high initiative into a position where line of sight cannot be drawn to it, but its initiative reveals some or all of the enemy warband.

The All-Seeing Eye of Numas allows you to see hidden units

From the rulebook (page 100):


  The bearer of the All-Seeing Eye can see all models on the table top, even if they are hidden or out of sight.


If you are lucky enough to have one of these, the enemy can never hide from you!

Arm your troops with spears

This will make his charge much less useful, since the Strike First ability means you will hit him before he can hit you.

Use terrain set up to destroy his chances at the edge of the board

If you are playing the standard rules for terrain placement for most scenarios, you are within your right to place terrain at the edge of the board that is horrible to defend. Then if you manage to win the roll for first set-up, choose the side he has designed with defence in mind and leave him with nothing worth hiding around.

Play a different scenario

If you play scenario 3 (wyrdstone hunt), scenario 4 (breakthrough), scenario 5 (street fight), scenario 7 (hidden treasure) or scenario 8 (occupy), there is a very high chance he will lose by using this tactic.

Meta-game things that may help you


Whenever he initiates this tactic declare a temporary alliance with someone (or everyone) else (if playing with more than two of you), and mob him in his nest. There may be some casualties to your alliance, but you should make quick work of this player's warband and teach him in the process that using this tactic is going to make the game less fun for him.
Teach yourself to measure distances by sight. Your opponent will end up out of cover and ready for shooting/charging if he declares a charge, but falls a half inch too short.
Talk to the player (as a group, and as nicely as possible) and just explain that while, yes, his preferred tactic is technically legal, it makes the game much less enjoyable to play for the rest of you.
Use his tactic right back against him. If you just hide at your starting location and keep passing exactly like him, he will quickly realise just how un-fun it is to be on the receiving end of it.
Create a list of your own scenarios, making sure that many of them either cannot be won by playing defensively (like scenarios 3, 7, &amp; 8), or actively deter defensive or stationary play.
If none of these things work, then I would suggest trying to play some games when he isn't invited.