Tbh, i didn't calculate it precisely so you got me there, but either way, it is most of it when there is in fact a runway in the reciprocal direction (ceiling providing) and an alternate that I'm sure was just fine and dandy.
I'm sure they have never had to tell you that info and thankfully i've never been in that situation they've needed to tell me, but obviously the controller thought this was a bad idea. I don't fly the 747 but is a 2300m wet runway going to work in a tailwind at a reasonable weight, let alone a 16kt one? Whilst I know it isn't his job to try to persuade the guy not to take it, obviously he was concerned that it might be out of limits and that perhaps giving the tailwind to a pilot that doesn't seem to be internalising the information given (a bloody strong tailwind), stating the obvious might have been useful in this instance to snap him out of it. I'm not sure of the name of the CRM model but there is one that tries to empower individuals to basically bark cold hard information with as much clarity as possible to stop someone from doing something stupid (RAISE model?), although I don't know how this would fit in to a controllers role as a service provider. I cant remember the exact details but there was a similar case in florida (i think?!) recently with a light twin, the pilot was told about a tailwind in excess of 20kts, he was just given the direction and perhaps was overloaded at that time that he didn't have the capacity to calculate the component. Perhaps someone more familiar with the 747 would suggest what a sensible RLD/FLD for a 16kt tailwind?