First off the authorization doesn't slow bleed anything.
It sets a deadline for either succeeding under bush's last attempt or accepting the failure as permanent.
Second the suplemental spending bill is in no way required to be exclusively for troops. In fact NONE of the previous supplemental budgets were and Bush never complained before.
Besides setting the budget is the CONGRESS' responsibility.
Third Bush has been granted MORE authority than is legal. He is being given the funds he asked for a LAST attempt.
If Bush is still FAILING in Sept his excess authorities will be pulled.