I think the SSPX approach is a little more like the traditional Spanish approach to the Jews, pre-St. Vincent Ferrer;
"At different times in Spanish history strenuous attempts had been made to convert the Jewish people, baptism or spoliation being the alternatives offered to them."
Conversion is usually instigated by the realization that the faith being proposed possesses Divine truth and that in turn is usually inspired by personal witness.
You would be incorrect then.