"perfect" is a weird word to use in stoicism, but I do think it can be used to justify that things "are the way they are" and shrug it off with some visualization.
both "screwed up" and "perfect" are judgements calls/perspectives, and panicking isn't going to change things (panic doesn't necessarily make something worse either)
you can't think of an example where it doesn't? I can. I'm not saying there is any virtue to it, but panic can subside without having had negative side effects on anything other than your mood
The first part of that sentence is opposite to what the author here suggests.