I cannot say for sure but I know they specifically state the essay is required so if he only took it one time without the essay, he has no score to report since the UC’s will only accept the SAT with that essay score. I would not write a letter, but call UCI admissions and any other UC he applied to get the information directly from the source.
And why is this coming up now since the UC’s will take up till the December sitting for the SAT or ACT which could have given him ample amount of time to retake if necessary.