A Bug's Life

It may not be a protest -- he may have had mild constipation (big, hard turd). If cats experience pain on defecation or urination, they associate it with the place they're squatting in, and so go somewhere else. It's the right time of year for cats to begin shedding, and if he swallows too much fur that can also contribute to difficult bowel movements -- if the turds are pointy or appear to be helf together with fibre, that's a warning sign.

Upshot -- it's probably a one-off, but if it recurs, consider a vet visit (to check for problems). Alternatively, try giving him a little bit of wet food in his diet, or katalax or similar dietary lubricant (for fur balls).