Curiosity – So I had a look at the Mahari Kara and, guess what? It’s not quite as you make it out to be. He starts off with the assumption that it is impossible to lap like a dog without kneeling, he therefore says that there were actually three groups – 1. those that knelt and somehow drunk (not explained how), 2. those that knelt, put their face to the water and lapped directly from the river, 3. those that somehow gathered water in their hands, stood up and then lapped from their hands. This is difficult for a number of reasons:
1. The pasuk is not mashma that there were any more than 2 groups – those that knelt and those that lapped. All the other mefarshim you quoted learn this way (Radak, Metzudos, Rashi, R’ Yeshaya).
2. It is entirely possible to lap without kneeling, one can bend over or lie flat, as I described above.
3. The difference between the first 2 groups is not explained. How did the first group drink, and why would the pasuk split them into two groups if they were both disqualified for the same reasons? It should simply have been enough to say that anyone who knelt, for whatever reason, was disqualified. Why split them?
4. The mechanism he proposes is not really possible. Try it for yourself – put a bucket of water on the floor, bend over or crouch down, cup some water in your hand and try standing up straight without spilling almost all of it. Then try drinking. You ain’t gonna get much.
Even if you wish to hold on to your Mahari Kara, the other mefarshim clearly do not learn like that (as it would require 3 groups where they have just 2) and if you want someone who be’feirush disagrees then the Ralbag says that those that lapped like a dog were chosen as it showed that they were fearless and not afraid to put their faces in the water so clearly they were not standing up…
Anyway, as I said before, even according to the Mahari Kara they were lapping from something – an action you described as being unfit for a ben torah. I’ve said it before and I’ll saying again – it’s not about the kneeling, no-one kneels to a water fountain.