Importantly, this was a bucket of water, rather than a more movie-appropriate swinging bucket of hardened-concrete to the face.
The latter--a potentially lethal booby trap--is illegal in many places, even if it's your own home. (Arguably for good reasons.)
it might not be if there is a visibly clear warning sign (IANAL though)
AFAIK this has been tested and failed. Booby traps of any kind are considered unmanned and can not be used as a self defense case. Only an individual human can
legally defend themselves and even that gets dicey depending on where one resides and what they say to the cops. It will be interesting if someone tests this with "AI", I predict that will also fail as it is also unmanned and there is no clear and present danger. Not a lawyer but watched countless videos from legal firms that firearm owners can become members of.