Negativity bias, trauma-based game design and learned helplessness in metagames

[Glorthindel]

I thought the question was more if some guy across the street mumbles fake Latin & sticks their finger in their ear 3 times, then crosses the street & the mercant gives them a free lunch, does that start a lynch mob?

That's the crux of the issue though, you have granted the Wizard several benefits that he does not have - spellcasting is not subtle, so the somatic component there is dodgy, and mumbling is straight out (and depending on the spell, you have possibly given him a free range bonus and removed the material components too). That Wizard is clearly and visibly spellcasting, and that changes the scenario significantly - in the analogy he as the very least has his sword in his hand (and very possibly a very large cannon).