Rules Conundrum: WHFB buildings, close combat and multi-character units

Guess who's back? Yay, it's me.

This edition of Rules Conundrum will be a little different. Why? 'Cause I say so. And also, because it's a weird thing, that has a fairly straightforward but completely unintuitive answer.

So, last night I had a game of Warhammer Fantasy. Watchtower scenario (oh, lord, how I hate it). Long story short, my general and Battle Standard Bearer (only survivors from a unit of Halberdiers) assault the Watchtower alone. Here's the fun bit, from the rules regarding assaulting a building:

"If characters, champions, or other models that can normally be singled out if they are in base contact are involved in the assault, then up to half the enemy models can choose to attack them [. . .]" (BRB, p. 128)

So, up to half the enemy models involved (five out of ten) can choose to attack my characters. Not each. Half his attacks are wasted, since there isn't a unit to attack instead.

And on that short note, I leave you for now. I'm hoping to get a commentary on my Tyranid list up within a couple of days. Here's to that working out.

Cheers.