Read other letters about this article
I believe you're confusing heroism and criminality. Assuming both Bush and Tamm broke the law, they would both be criminals. To Glenn and many others, Tamm is a hero for exposing, and now fighting an administration rife with corrupt and unlawful behavior. Further, laws may exist wish may exonerate Tamm based on his duty not to turn a blind eye to illegal activity. Others, I suppose, believe Bush's unlawful behavior was heroic in protecting citizens.
Regardless, Glenn isn't proposing that either is above the law, but rather only the less powerful are prosecuted.