Osborn's brain boils over on a regular basis, and none of the others can be relied upon to not pursue their own goals, to not even broach whether they can be trusted.
And just where do they go from here? Everyone being slaves to Mephisto, because Peter and MJ's deal opened some door? They can't say all this is just shaking up the status quo, because no situation is around long enough nowadays to be a status quo.