Supposing he doesn't practice what he preaches, which is not true, does that make anything he says any less true? Do you make choices based squarely on what others do, or do you make up your own mind and act accordingly?
Do you apply such standards on liberals? They certainly don't practice what they preach. Many of the richest people on Earth are liberals, and you don't see them forking over more of their wealth to government. You don't see them going green; they're as polluting, if not more so, than anyone else. They don't give as much to charity. They exempt themselves from Obamacare.