They may not agree with this, but they are, in essence, saying God is not Sovereign over Satan. That's the (il)logic of their view.
Some that adhere to this fallacious understanding are the same type that say God cannot do anything on earth unless man allows him to through prayer. To make the claim that Christ is not King and God is not in control is at it's core blasphemy and a severe attack on the character of God. And by logical extension, if God is not in control, then Satan is more powerful than we think and could actually win the fight. The only way this statement isn't possible is if God is in absolute control and Christ reigns as King, from eternity past, now, and forever.
All this is really scary because people are essentially giving glory to Satan that does not belong to him but to Jesus Christ. "Satan is in control; he rules the earth unchecked; he is king for the time being; he is god of the world (everyone in the world)". This is exaltation of Satan over Christ.