Interesting thought but, firstly, I would say that the hypothetical premise could barely be thought of as possible (the law makers are generally democratically elected and cannot therefore maintain power for long intervals).
But the theme of delusion has the greatest flaw: even if there were a tyrannical, all-powerful despot, their iron grip would be too evident to be delusory. The law is only law if people knowingly abide by it (there is thus again no delusion).
The only case they could be deluded is under some unfathomable circumstance (too unfathomable for me to give an example).