Jesting aside, absolutely. The efforts of some of these minor celebs in recent years has gone way beyond sitting in baths of beans. Walliams, Izzard, McKichan & Skelton in particular have excelled themselves, and this effort looks well worth supporting. Of course, the way for big name sponsored bike rides was started by Geoff Thomas, and Lawrence Dallaglio was recently on his bike too.
If it gets a few kids out on their bikes, that's brilliant.