David Letterman has made a couple of trips to Iraq to visit the troops. What can be assumed from those gestures? I’m not sure but what can be assumed because Tiger isn’t going as you seem to think is required to fully support the troops.
Leno is a commentator, O'Reilly is a commentator, Franken is (was) a "commentator", and the same with Ingraham, Malkin, the bloggers who've gone, etc.
Tiger's not a commentator, he's not a performer, but he IS of military heritage and I'll bet he'd like to show his support, but wonders "What the heck can I offer to these guys by going to LSA Anaconda or Camp Victory?"
He puts it best as is noted above: "I just want to say, ‘Thank you’ in some way, and this is our way of being able to do that".