My reading of this is that he did not witness this with his own eyes; if you read a few (brief) pages back, he seems to be quoting from books that he has read about Freemasonry.
LABAW: TI GAMENG ITI KAMALIG TI GLU(Maysa a Rebiu)AWAN katukadna a gameng iti kamalig ti GUMIL La Union ti libro a LABAW.