Hmm, sorry about missing your point
. Psion count doesn't mean squat, it's just raw power. The Shiba sibling brother has a huge psion count, but he's not an exceptional magician. As for talent, they wouldn't know since doing disintegration and restoration is akin to arithmetic in math, the basic of basic. What make Tatsuya disintegration special is right now, he took the arithmetic to the max and make new theorem with it, but back then, what the other see him is basically someone able to do simple arithmetic, nothing special.
BTW, up until vol 8, I haven't seen the so-called Yotsuba current mistreatment on him(beside trying to separate him from Miyuki), so I wonder if it will hapen in the future volume? All I've read so far regarding his mistreatment from Yotsuba is only the experiment and things in the past before the event in vol 8.