And the wedding took place on Vulcan!
And I don't think anybody (except T'Pring) really expected a lust-crazed battle to the death. My impression was that T'Pring invoked an ancient tradition that was rarely if ever acted on those days.
Kind of like the part in a modern wedding ceremony where the officiate asks the guests if anyone present has any objections to the union. Nobody present really expects anyone to stand up and say anything. It's just a formality.
I'm not sure Spock getting married to someone he clearly hardly knows and has little to do with in 'Amok Time' would have been a happy moment for Amanda, honestly. It's just another element of Vulcan culture she may have had little choice but to play along with.
Remember, Amanda knows full well that Sarek dealt with his Pon Farr with Sybok's mother, but in the end his heart was with Amanda. We saw the same thing happen with T'Pol, Koss, and Trip (which means this sort of thing is probably common with Vulcans). Why would Amanda wish this same sort of fate for her son?
I think Amanda would much prefer that her son spend the rest of his life with someone who understands and accepts him, which T'Pring clearly didn't.
Even given that Spock could die due to his Pon Farr, Amanda may very well have preferred he dealt with it via Orion escort, as foreign as the idea may seem to current 21st century thinking. The Orion escort wouldn't be doing anything she wasn't already doing, and then after the Pon Farr is dealt with Spock and the escort can go on their separate ways. I have no idea what the "legality" of this would be under 23rd century Federation law, but surely an exception could be made considering Spock's life was at stake.
In fact, I wouldn't be surprised if, in-universe, many Vulcans found the above idea far more logical than tying their lives to someone they barely know in some childhood betrothal. And the Orions probably made a big business from this, "helping" Vulcans through Pon Farr who found life long marriage to strangers illogical. Spock's family probably went with the betrothal option because they are high class nobility, or whatever (have estates dating centuries, ties with T'Pau, big shot ambassador, etc).
Strictly speaking, this is probably far more moral than tying Spock to someone (for over a century of life) that he barely knows and has little to do with, very likely messing up Spock's own wishes for his life directions as well as T'Pring's (which were clearly headed in a different direction from Spock's as well, as she wanted a life with Stonn).
(although to be fair this might have been valid...)
