I've long thought Aaron was a classy guy for the pressures he had to handle. And given denial of things such as the Holocaust by people who were alive at the time (admittedly not the best comparison), I don't blame him for holding onto letters so as to avoid the years later of "no, they never did that."
But that said - stay out of the political arena or get in. Don't halfway do it. And seriously - does Hank really believe there's any difference in how the GOP treats Obama and how they would treat a white President? They impeached the last white Democrat!!! (I could point out how Hank's party of choice housed a former Klansman who tried to filibuster the Civil Rights Bill in 1964 while Hank was playing in that bastion of integration of Milwaukee, but it would be a waste of time).
Look, Hank is 80 and can say what he wants. But just don't be surprised if this lowers the view people have of you. They might decide, Hank, you're not all that different than Barry Bonds. And that can only be bad for Aaron.