Well, you can read it that way if you wish, but George IV tried basically the same argument nearly 200 years ago, and it was not accepted then, and it's not accepted in British constitutional law now. Bear in mind that the 1820s were the great period of reform of the British constitution, ending in the Great Reform Act of 1832. This is the time that British government took on the form, more or less, that is recognised today.
Implying that the clergy or the parliament holds its powers in perpetuity, with absolute right of abusing them (implying a totalitarian bent on their part), is implying an abolition of prerogative where none exists.
Avoiding a totalitarian government on the part of Parliament is the reason why the Monarch does retain power to intervene on constitutional issues, but avoiding a totalitarian government on the part of the Monarch is why they only have that power on certain defined issues.
Remember, this oath is sworn to God.
Yes, it is - but it also says what it says. That last sentence is part of the Oath, and has to be followed like any other part.