That is a very interesting question. Probably not.

The president's power to pardon cannot be infringed upon. That is very clear from SC case law. So no one can tell the president who he can and cannot pardon (although the whole "himself" issue hasn't been decided.) That said, if the president pardons everyone involved in an investigation that includes himself, the obstruction argument would definitely be there. The SC would probably find that if obstruction allegations/charges for pardons were permitted, it would completely undermine the constitutional power of pardons. Ford could of been accused of obstructing Justice in Nixon's investigation, but that suggestion would be contrary to the purpose of the pardon power. Also, when conflicting, the constitution controls over federal laws, so that supremacy would negate the obstruction of justice charges.

I am taking the bar exam on Tuesday. Constitutional law is a big part of it. Presidential powers has the least case law of any article of the constitution, and what little exists is primary from Nixon and Clinton. I was just telling a friend that people taking the bar two years from now are probably going to have a whole lot more presidential powers doctrine to learn...