I'm just curious as to why a firearms manufacturing company would make a rifle with a "ridiculous twist", do they not want their rifles to shoot good? Seems like they would do some research and find out what twist works best.
Any number of reasons but they are all related to profitability and assuming that people will by the “popular” caliber and not understand the purpose or requirements in order to fully realize the benefits that the caliber can offer.
Balistically there really isn’t a good reason to choose a 28 Nosler unless you are going to shoot 195 grain Bergers. If you are going to shoot lighter bullets there are calibers that do it as well or better. If you are going to run the 195 grain Bergers you need at least a 1:8.5” twist and a 1:8” would be better.
If you just want a 28 Nosler so you can be a cool kid and say that you have a 28 Nosler then buy whatever you want. It truly doesn’t matter to me. But the reason the 28 is popular with long range hunting folks is the BC of the 195 grain Berger and the ability to sling it over 3,000 fps.
Edit: In the case of the gun you recommended (Christensen Arms Mesa), per their website every 7mm caliber offering is spun up in a 1:9” barrel. That leads me to believe that the reason for a 1:9” twist in that particular case is nothing more than their ability to reduce costs by buying all of their Mesa barrels in a single twist rate.
Also, the Mesa weighs 7.9 lbs so it would be out for the OP anyway.