Casting through a ward, Should I call shenanigans? Options

[Tanegar]

OK, at the last session one of my players asked me a question I wasn't ready for. He wanted to know, if you can poke your finger through a ward, can you channel mana through your fingertip and cast a spell on a target inside the ward as if your whole body was inside.

The situation is this: there's an item that the PCs need to acquire, located in an office. The office is warded, and the ward is constructed in such a way that its boundaries are coterminous (I think that's the word I want) with the office walls; that is, the boundaries of the ward are inside the walls (and floor, and ceiling). The player wants to drill a hole in the ceiling, have the magician PC (different player) poke his finger through the hole, and thereby through the ward, and cast Influence to make someone in the office toss the item out the window. There was also some discussion of a pair of mage-sight goggles; I think he wants to slip the fiber-optic cable through the hole, and cast the spell that way.

I said yes, but really the question caught me off guard. The more I think about it, the more I think it's a bad idea to allow this. I'm not aware of any rule or fluff that says spells emanate from a particular body part. I also think it trivializes wards as a defense against magic.

Dumpshock hive mind, should I call shenanigans on this player?