Alot of good points brought up in this thread, and some expressing opinion that seems to carry a bit of bias. Every rifle is individual to the owners needs and expectations.
Newbies are easy to spot weather via; face to face, e-mail, or phone.
When I make a contact, and cartrige selection comes up I always ask the folowing questions;
Realisticly what yardages to you plan on harvesting game?
What species of game will be the largest you hunt?
Do you oppose a muzzle brake or are you good with one?(suprising to some but many customers actually want them)
What would be your ideal rifle weight?
Are you an experienced handloader? or do you plan on using factory ammo?
With out these answers, it is hard to fit a gun to a customer, final weight may be dependent on the component selection. Some new guys think a 9lb 300/338 super banger is easy to build with a 30" barrel and an A-5 stock, and NF scope.
Well they need a reality check, or a mid range 7mm.
As far as what went on with the OP friend;
If the answer to the last question is "factory" The 300 win mag is a perfect choice, in a LR elk gun, many great accurate factory load offering.
If he wanted a 9.5lb rifle, again a 300wm with a 26" barrel, near perfect.
If he wanted a 8.5lb gun I would have pushed him hard toward a short mag.
If he asked for a 12-15lb rifle with a brake, sure step up to a RUM based cartrige.
BUT NONE OF US EXCEPT George know exactly what the parameters of the build are, because he holds the work order.
Do I have favorite cartiges sure, many, I use one over the other based on; range, gun weight, game, terain and confidence. A newbie needs to start somewhere to gain experience and learn what he likes, under what conditions. At least the OPs friend is off to a good start.
The only point I disagree with is that at 1997 yards that elk would have dropped on his dick!