Lowly SLF here but is .3 tonnes legal for landing fuel at an alternate? Al Ain closer perhaps?
Diversions to the nearest airport aren't always the most sensible. For example, you might not have a contract with a handling company, their infrastructure might not be up to scratch, it might not be open, there might not be connecting flights etc.
Regarding the .3 tonnes figure I think you have missed the point. I don't fly a 737 but I'm going to guess that it burns about 40 kg/minute. So if you have 4.7t in the tanks (as this one allegedly did) and a 75 minute diversion you'll arrive with about 1.7t which will allow say 800 kgs for two additional approaches AND half at least 30 minutes holding. When you fly a plane for a living you have have a good idea of your endurance and rough idea of aircraft's performance in your head. The figures aren't complicated and most 11 year olds would be able to handle them. Having the rough'n'ready numbers means that when you bugger up reading a table, miss-type a value, incorrectly enter a route (which all of us do), you know that the answer you have just been given is rubbish. Also, if the systems let you down, you can go back to basics and still not be in trouble.
And while we are here talking about numbers, we mustn't forget that there are two people on the flight deck. Both of you should be cross-checking each others' rough workings. Plans for diversions should be really simple and explainable to the other guy. So when it starts getting marginal, both of you are clear about what will happen and will have confidence the numbers you have in front of you.
As for the 25 knot crosswind I'm afraid I can't see the reason unless the DGCA thinks that this either this company's pilots and/or its training are not up to scratch.
PM