Yes, with SSPV and Mendez, that was a special case, and I totally get that. But it should be a rare exception, and as you point out, the SSPV should have been forthcoming about at least the information you cite. Again, tell the faithful, and let them make up their own minds.
Silence doesn't inspire confidence.
Right. See, at least with the SSPV, they're on record as emphatically disputing the validity of the new rites of ordination and episcopal consecration (it was one of the main reasons for their split from SSPX), and they are so "strict" (to a fault) about it that they question the validity of 90% of the Traditional Catholic bishops and priests out there (not only the Thuc line, but also Bishop Williamson ... due to the "one hand" problem -- or, rather, made-up problem). So you can be sure they wouldn't be messing around with dubious orders (I think). Now, if I didn't know The Nine personally, and were just someone, say, from a foreign country, who didn't know them from the Old Catholics down the street, I wouldn't darken the door of their chapel either.