It is NOT SLANDER or a Lie.  Father Richard Rohr calls himself heterodox:

"The Franciscan Tradition in which I’ve been formed is an “alternative orthodoxy” or heterodoxy. While we are part of the RC faith and embrace the great Christian Tradition, we are not mainstream".  https://cac.org/a-third-way-2017-05-28/

He implies that St. Francis himself was heterodox which is a lie
"You may be wondering, “How can Franciscanism be an alternative and still be called orthodox (right and true)?” Heterodoxy is precisely a third something in between orthodoxy and heresy! I sincerely think Francis found a Third Way, which is the creative and courageous role of a prophet and a mystic."

Francis of Assisi was an orthodox, faithful son of the Church.  This is from his Rule 1221:

"Let all brothers be Catholic and live and speak in a Catholic manner.  But if anyone err from the Catholic faith and life in word or in deed, and will not amend, let him be altogether expelled from our fraternity."