The poster knows that there are many people who identify themselves as traditional Catholics who have nothing to do with the SSPX, and although there is no mention of the SSPX in the article the poster chose to insert "SSPX" into the original title of article. It has since been changed back to the original title by the moderator.
Gibson is the father of actor-director Mel Gibson and a follower of an ultraconservative branch of Catholicism that rejects the liturgical reforms adopted in the early 1960s resulting from the Second Vatican Council -- commonly referred to as Vatican II. The worldwide movement was started by the late Marcel Lefebvre, a French bishop who broke with the Vatican and began appointing his own bishops and ordaining priests. There are no accurate figures on membership.
The four letters "SSPX" are not mentioned. However, it's founder most certainly is. As is his "worldwide movement." Is the worldwide movement which Lefebvre founded known as the SSPX?
Anyone not fully acquainted with Gibson or his beliefs, could legitimately conclude from this that he was somehow affiliated with it.
Again, the primary error here is with the journalist. It is he who introduces the name of Lefebvre and his "worldwide movement." However, he deserves to be cut a little slack on this one as does the poster. The pedigree of every inhabitant of the sedevacantist fever swamp is known to but a few.