Can "then" be used as an interrupter?

When "then" is used to mean therefore, must it follow the same punctuation rules as all other interrupters, and therefore be set off with commas?

So for instance, are the following punctuated properly, or could you afford to lose a comma or two?

"How is it, then, that you get off completely scot-free?"

"Could it be, then, that he has finally changed his ways?"