The way it went down in story, the whole thing with Eizan's ploy to bring Soma down ended up being centred around Mimasaka's Shokugeki and the implication he was the one who arranged for Soma to go up against Alice in the Quarter Finals. Turns out that Eizan himself couldn't really do much to actively bring Soma down, so he just tried to do it in this half-assed manner that ended up powering up Soma even more. It was just sort of weak after Eizan's declaration of bringing Soma down during the tournament, but I suppose given Isshiki's speach Eizan is meant to be sort of a pathetic character.
(The strange thing about it is that Isshiki decided to not interfere with Eizan's scheme at any point, but I guess he just had enough faith in Soma and Eizan wasn't really doing anything "wrong")
From a story telling perspective, Eizan getting angry at Soma was always an excuse just to set him up as the replacement "Person Who Is Trying To Get Soma Expelled from Totauki" (trademark) for the tournament arc and being maybe a long term, genuine antagonist for Soma to go up against. We used to have Erina in that role, but obviously the writer realised that wouldn't be good development for her so in came Eizan (and Erina got ignored for 60+ chapters).
