Casual assurance is unusual in everyday speech so I am assuming that it is media speak. The inference is that the subject is unimportant and may or may not be sent on.
Casual assurance is almost an oxymoron.
Casual assurance in this context refers to "quick', "curt", "short" decision, statement, assertion, because 'regional media' doesn't bring much to the table, therefore is very vague.
But that's just my assumption.