I think the http-equiv="Refresh" redirect is done so that the http referer header is from t.co, and not twitter.com (or whereever the user clicked the link from

I think the http-equiv="Refresh" redirect is done so that the http referer header is from t.co, and not twitter.com (or whereever the user clicked the link from). (I don't think rel='noreferrer' is fully supported by all browsers)