Typical Dispy hermeneutic. Since when has the "bride" of Christ been referred to as a "he"? (the Greek itself is in the neuter gender when its used in v6)
For what its worth, the traditional understanding (that is, for the past two thousand years) is that this is likely a civil government or restraint. Indeed, the primitive Christians believed that this "restraint" was the Roman Empire and by which they prayed for its peace and welfare, as knowing when the Roman Empire were to be disolved and fall into pieces, the empire of the man of sin would be raised upon its ruins.
The normal Dispy rebuttal is based on the bias that "the man of sin" can only be a singular person. This is based on mishandling the Scriptures and ignoring, not only the historical evidence, but the language of the text itself which naturally leads one to understand "man of sin" as being a sucession of men holding the antichrist demeanor. Think of this as the spiritual equivalent of Ground Hog Day, where Satan keeps playing different strategies with different leaders until he achieves the pinnacle of his wickedness as typed in the Days of Noah. Since it doesn't fit the Dispensational template, then the normal hermeneutic is chucked for the much cooler imposition of a Hollywood master bad guy taking the scene.
The Church the Body of Christ is obviously referred to as HE. The One New Man is well HE.