The danger does not come directly, but indirectly from Cardinal Schönborn. It is quite true that the Cardinal cannot do anything against the SSPX from an ecclesiastical point of view. He can, however, try to make use of the state to achieve his goals. An allegedly discriminatory statement in a sermon, an allegedly problematic statement in a book that is being sold... It is easy to find pretexts to activate the public prosecutor's office and to fight the SSPX with massive problems, expensive lawsuits and negative headlines.
Vienna may be a big city, but in some ways it is also just a small village. The important figures in politics, business and the church are well known to each other or even friends (and, of course, they all are liberal and politically left-wing). It’s not difficult for the Cardinal to call in a favor.
These considerations have not the least to do with timidity. Of course you can “courageously”, loudly and provocatively proclaim the catholic teachings to the Freemasons in power, but one will get then very fast problems with the justice. The registered association of the SSPX will be dissolved and all activities of the SSPX, then stigmatized as “extreme association” will be forbidden. (Perhaps one or the other must also go to prison. But that the good God will then send an angel for such foolish “courage” to free the prisoners, as it happened with St. Peter, is not so sure.)
“Be ye therefore wise as serpents” (Mt 10,16).
The video that Gloria.tv linked to the article doesn’t show actual footage or even the SSPX. It’s from 2016. Here is the link to the original video, actually on the website of the Minoritenkirche:
http://www.minoritenkirche-wien.info/daten/lnk2016/fuenfherrenamt-video.htm