And, yes, it's purely ornamental as far as I can tell. A tilde's just another punctuation marks, albeit a rarely used one. In theory,
Mike could've chosen an exclamation mark, question mark, or asterisk, but they wouldn't have looked as pretty there in the purple box as the tilde does imo.
Miranda
"Multiple exclamation marks are a sure sign of diseased mind" -- Terry Pratchett
!!!!!!!!!! ← Maud, John, Alice, Peter, Emma, Edith, Lewis, Henry, Isabel, and Joseph