Brilliant post Phphion really, really insightful.
Aurea your son sounds truly outstanding. I'm sure he'll have no bother getting offers, but it can't do any harm to put in a less sought after university as choice 5.
For context, DS made all choices in October. State school, non-contextual. He received offers from Edinburgh (3 weeks) and Strathclyde (5 weeks) really quickly. Glasgow was late Jan and St As last week! Oxford rejected him before interview (we already discussed months ago on MN that Scots are disadvantaged by Highers. For DS, as his Adv Higher Maths went on he realised loads of the MAT paper he found problematic was covered comprehensively- but this was too late. I think it was the MAT result that was the nail in the coffin. If we had known this we would have pushed for an early Adv H or located a tutor. For your DS he will have done Adv H Maths, a huge, huge bonus).
I must disagree with EightyTwenty that Glasgow is not as 'top' a university as the others you've listed. Traditionally it is difficult to get in- lots of DS's friends haven't this year. I've already mentioned before that 2 of my own pupils didn't get into medicine at Glasgow, but did get into Edinburgh, and a colleague's daughter got into Law at both Edinburgh and Glasgow but was rejected from Strathclyde (a super reputation for law). Strathclyde is particularly known for the Sciences and being cutting edge, so perhaps might be a possible choice?
I strangely know 2 of the country's top judges: my cousin (Strathclyde) and a school friend (Glasgow). Both attended my school- very ordinary comprehensive in our town just outside Glasgow. They both could not have afforded to live away from home, therefore excellent universities on their doorstep were a huge advantage.
I'm sure he'll be fine whetever you choose.