So I'm no senior at 35. But I have difficulty wrapping my head around the economic reasons for an outfitter, to provide a discount to seniors, above other population groups.
People above 65, usually retired, no more kids in the house, hopefully after a successful career are rather the ones with the funds to be able to go on a safari. Usually it is not the 20-40 year olds with heaps of children care costs, and being at the start of their career.
I could perhaps see a discount for less mobile senior's, who are mostly expecting to just sit in a blind of sorts, as this would save on fuel costs, and probably personnel costs overall for the outfitter. But that would rather be a discount due to the mode of hunting, rather than the age of the hunter.
Discounts or cheap offers for 20-30 year olds for cull's/cheap trophy animals make a lot more economic sense however, the same for father/son deals. If an outfitter can light the fire for Africa and hunting safari's in the hearts of younger people (who most likely will not have a strong financial leg to stand on yet) they are investing into their future customer base. They might be able to sell a few extra safaris, over the course of someone's life, instead of having only marketed to the +50 year olds.