In AAA! There isn’t a Kyle Tucker, Arenado, Bryan Reynolds, Freddie Freeman, et al. in AAA. Those type of batters won’t be fooled as easily as AAA batters and will punish mistakes more. Until Misiorowski can consistently command his stuff there’s no reason to even consider him.
As for Dunn, the Brewers gave him two bites at the apple in the majors and he didn’t seize the opportunity. Since the did trade for him intuition says he will likely get another shot but he is likely the 40th man on the roster (maybe 38 or 39 depending on views of Thomas and Capra) so there is some urgency for him to go to AAA and perform.