Would this be a good option for people with sensitive skin or rosacea?

I wouldn't recommend it for two reasons. First, 20% concentration of a single active ingredient is high, even though it seems to be not particularly irritating. There is some data that shows that Ascorbyl Tetraisopalmitate could trigger some inflammatory pathways unless stabilized in the formulation - we do not know for sure, but it's not worth risking it for the skin with rosacea. And that's my second point: we actually are not sure how effective this vitamin C derivative is actually in skin, so it's too much risk for very sensitive skin.