One day there will be a case that puts it to the test.
Until then, enjoy the loophole!
It's not a loophole - it's the law as written, which is why the government had to change it on their website recently after someone, who didn't know what they were doing, made the same same mistake as you.
You clearly have still not got it, despite the many times it been explained to you, so here it is one more time.
OUTPUT POWER is the power that comes out of whatever you're referring to. It could be for the motor, the wheel or the vehicle, all of which can be significantly different, so you have to specify which one you are referring to.
INPUT POWER is how much power comes out of the battery, which is regulated by the controller's current limit subject to any settings, and the back emf that depends on motor speed. It can be easily measured. It varies all the time while riding even if you select maximum power.
RATED POWER is the power that the motor can run at without overheating, and is what the product engineer decides it should be considering the
adverse conditions that the motor might have to endure. Typically, they would use a factor of 3 or more for headroom because of the varied external conditions that can cause a motor to overheat. There are normally regulations that cause a manufacturer to write the rated power on any motor they make.
The UK law says that the RATED CONTINUOUS POWER of an EAPC must not exceed 250w. Again, someone doesn't know what they're doing because the word "continuous" is superfluous, as the rated power can't change, so is always continuous. Translating what they say into normal English would be: The power that the motor can continuously run at without overheating continuously must be no more than 250w.
The law has always related to rated power, never output power and never input power, so any ideas about how much power is allowed is just a figment of your imagination based on failure to either read or understand what the law is.