Reddit got caught unprepared by the protests, they are probably working on a shadow mod feature and forgot to hide it from the log. Deleting an already removed post is a fairly inconspicuous way to demo the feature.
"I'll let them know that the username is appearing in the log."
Note it wasn't: "that shouldn't have been done" or "that was due to XYZ", nope it was a "crap, you shouldn't have seen that in the log, we'll make sure it doesn't show up next time"
Not quite. This isn't an uncommon thing and appears in the log under the name "Anti-Evil Operations" (yes, really). In this case, it appears the admin probably didn't activate their admin status properly or something.
It isn't that they want to hide the action, it's just not meant to appear under a personal username.