OK, so Townsend could have given a better answer than saying Iraq is the center of the war on terrorism because... Bush says it is. (And because bin Laden is "clear" about believing the same thing -- of course, were I bin Laden, I'd want to tie the U.S. down in Iraq, far away from where I am and what I'm plotting. But anyway.)
When considering a global, decentralized network (or movement, if you prefer), it's misleading to suggest that there's a single, fixed "center" that would mean the destruction of the network if defeated. But the effort to avoid affixing special significance on Pakistan arises for a simple reason: neither the administration nor its critics is prepared to invade Pakistan. Even the infiltration of special forces and intelligence assets into the area is potentially destabilizing. Bush once said before 9/11, when casting doubt on a Richard Clarke-authored plan to go after al-Qaeda in Afghanistan, that he didn't want to "swat at flies." In Pakistan, fly-swatting is the most anyone has proposed against a well-entrenched AQSL. Welcome back to 2001, when the most robust option against a looming al-Qaeda threat is exactly the one that remains unthinkable.
That leaves the U.S. with just one choice: backing Pervez Musharraf. Townsend attempted to shift away from the conclusion that Musharraf is the central figure in the South Asian theater of the war on terrorism, but it could hardly be otherwise. Until the U.S. is prepared to risk the destabilization of Pakistan by moving U.S. and allied troops into the FATA, there's little other option except getting Musharraf, already on shaky political ground, to clamp down on the area. This is where we are after six years, two wars, 4,000 U.S. troop deaths and around half a trillion dollars -- except with exhausted military resources and far more recruits for al-Qaeda.