Sure, that works if we are talking about a first post in a topic.
Yes, I guess that would be a viable workaround, but it kind of defeats the purpose of a flag.
Usually the offender gets notified when their post is flagged and they get the chance to edit their post and re-writing the offensive part to make the post reappear. They won’t have that chance if the post is deleted.
PS: Also deleting a flagged post resolves the flags…