It's not the executive's job to check them. That's the job of the legislature. If they are doing something wrong, they can be impeached. In Florida, they can be recalled, I believe.
Separation of powers certainly doesn't seem to mean much to you if it doesn't get you what you want. It is your 'interpretation' that the court "killed a citizen by cruel and unusual punishment", it's not a 'fact'. Fight for your interpretation, don't declare it to be absolutely true. You aren't a dictator, regardless of how much you might want to be. You need to convince other people you are right and change the system through legitimate means.
Like most fanatics, you can't wait that long.
Of course it is. He swore to protect and uphold the Constitution. That's a solemn oath.
That's the job of the legislature.
In MA, the legislature HAD checked the out of control "Goodridge" court. They ignored them. If Romney had simply ignored them too, the legislative and the executive branches would have checked these four out-of-control leftist judges. But no, Romney saw fit to side with the lawless decision of the court and joined them in checking the legislature. "Stroke of the pen, law of the land. Pretty cool!" But, there is still no law.
Again, Thomas Jefferson:
"...the Federal Judiciary; an irresponsible body (for impeachment is scarcely a scarecrow), working like gravity by night and by day, gaining a little today and a little tomorrow, and advancing its noiseless step like a thief, over the field of jurisdiction, until all shall be usurped from the States, and the government of all be consolidated into one. When all government... in little as in great things, shall be drawn to Washington as the centre of all power, it will render powerless the checks provided of one government on another and will become as venal and oppressive as the government from which we separated."
His comments apply equally to the state courts, too.
The whole legal profession is full of judicial supremacists these days, of course. It's their power we're talking about.