It's not nutritious - they can't digest it - but it's not bad for them either. He'll just hork it up in hairballs later (which is also normal).

If you opt for hairball medicine, check to see whether it's got petroleum in it. Petroleum itself is harmless, but it can stop a cat from being able to absorb nutrients from his food. A bit of psyllium-seed fiber supplement is safe and reduces hairballs, and doesn't interfere with nutrition.

Love, Columbine