F1 has fallen on a lull...they barely have enough cars to compete (most tracks they race at have contracted a minimum number of cars)...suspending Toyota would take out 2 cars and they may lose a race or two on the schedule next year

also Toyota gives lots of money to each venue it races in (all mfgrs do this, but Toyota gives more than any other mfgr)...this creates reliance by the racing series on Toyota and forces it to sometimes do what Toyota wants (i.e. how CART was forced to break its own rules)