alt Hacker Newsif i sent an email to my ceo and they replied with typos and bad grammar, i wouldn't think "wow, they are flexing their privilege to be able to do that".
i would be excited that i'm being treated as a member of the inner circle and they can speak freely and casually with me.
Some people think texts are for quick one-off messages and emails are for longer more thoughtful missives.
But (a) most corporate communication isn't by text, and (b) the CEO is probably from a time when there weren't any texts, so emails themselves were often used casually, in lieu of sticky notes.
In any case, I'm with you. The trope of microaggressions is way overused, and applying it to someone who is usefully communicating with you is rubbish.