Wow!
As did I. wiki is very contradictory with its 'facts' in this manner. I was hoping you had something else.
When you have something more solid, like some document from that era, then let us know.
Meanwhile, this should be dismissed as unsubstantiated rumor.
From one of those links, http://www.newmanconnection.com/faith/saint/blessed-junipero-serra-ofm;
Sound like a whack-job.