Critics of Buffett and his tax strategies don't really understand that what he does is not illegal and is socially progressive.  He doesn't avoid taxes.  What he does is avoid taxable income.  He does this by buying high cash flow companies that pay dividends and then canceling the dividends and using the extra income to buy more companies.  Additionally he improves efficiency where he can.  The result is no or very little taxable income.  So his wealth is on paper.  If he should ever sell any of his holdings, he will be taxed at the maximum possible rates.  But he's giving it all to charity.  This is all known as the Buffet Loophole and the IRS doesn't seem to care too much about it.  Why should you?

In doing what he does, he has created tens of thousands of good high paying jobs with excellent benefits that avoid governmental exposure for such things as health care and social security.  In his view, the private sector is better equipped and more efficient than government redistribution of wealth.  

He lives very frugally and does not flaunt his wealth at all.  He eats at McDonalds, literally. His  view is that if you are wealthy, capitalizing your gains then you should pay the taxes on it.  Note that he would be subject to the same tax hikes he preaches, so he too would be paying higher taxes than he does now.  And he's OK with that.

Your comment about him owning trains that haul oil but that he's against Keystone XL is laughable.  Trains carry all sorts of freight and they are a lot safer hauling oil than a pipeline, that is sure to leak, that runs under watershed and reservoirs that supply drinking water to millions of people downstream.

Add to that, he is genuinely nice person.  So your beef with him is what again?