Yes, but why would he even attempt something so awkward and strange for him, unless his motivations were along the lines of my proposed theorem ...? Not unlike the applause Heywood Floydd received from his costars in 2001: A Space Odyssey, after his rather stilted monologue ...
To interpret Soval's applause at the end of the speech in this way would imply that you may have missed the fact by the time Archer delivers his speech, Soval has gained much respect for humans. I think it started with the debriefing in Home, after Archer's version of the events in Impulse are corroborated by T'Pol. Well that and the fact that Archer and his crew had managed to save both the Earth and Vulcan when they destroyed the Expanse.
By the writers allowing Soval to show his appreciation and respect for Archer and the humans by doing something as un-Vulcan like as applauding, it was like Manny was acknowledging how bad Archer's previous speeches had been and just how much better the Terra Prime speech was.
Don't forget this exchange in Home
ARCHER: Ambassador. I want to apologise for what I said to you the other day. I was out of line.
SOVAL: Yes, you were.
ARCHER: I'm glad we can finally agree on something. SOVAL: Captain. Your actions, while being morally questionable, were necessary. I opposed your appointment as captain of Enterprise, but it's obvious now that I was wrong. T'Pol has told me that the Expanse would have someday encompassed hundreds of systems, including Vulcan. You've done a great service for both our worlds. (holds out his hand) Thank you.
...and the trust Soval placed in Archer when Star Fleet headquarters was bombed.
Plenty of respect and trust shown by Soval with regard to Archer.