The guillotine might not work out so well when the king has an unflinchingly loyal army of robots.
So sure, let's say a first generation of paranoid and intelligent "technofeudal-kings" ends up being invincible due to an army of robots. It does not matter, because eventually kings get lazy/stupid/inbred (probably a combination of all those) and then is when their robots get hacked or at least just free, and the laser-guillotines will end up being used.
"Ozymandias" is a deeply human and constant idea. Which technology is supporting a regime is irrelevant, as orders will always decay due to the human factor. And even robots, made based on our image, shall be human.
The specifics of technology have historically been largely irrelevant due to the human factor. There were always humans wielding the technology, and the loyalty of those humans was subject to change. Without that it's not at all obvious to me that a dictator can be toppled absent blatant user error. It's not even immediately clear that user error would fall within the realm of being a reasonable possibility when the tools themselves possess human level or better intelligence.
Now, if the AI reigns alone without any control in a paperclip maximizer, or worse, like an AM scenario, we're royally fucked (pun intented).