Ozzy47 and Painbaker, a winning team!
They are among my favorite developers and some of the most honest and helpful people I have dealt with in the XenForo community.
When I asked them if it was possible to create such kind of add-on, they immediately showed to be very collaborative.
They also took care of the development while listening to my needs and then developed the add-on in no time.
Many of their add-ons are free, but they all deserve to be paid!
"[OzzModz] Hide Thread From Guests" works like a charm!