How does it make any sense that Fr. Goldade get chosen for that reason instead of, for example, the current prior or un-canonical pastor of St. Mary's themselves: Fr. Patrick Rutledge or Fr. Jonathan Loop respectively?
Uhm, because Father Goldade is a native St. Marysite, and neither of those other two are ... ?

So, first qualification, a sine qua non, is that each of the chosen had to be obsequious "company men", yes-men to the current regime, and liberally-inclined +Fellay-ites who believe that V2 is "95% Catholic".
After that you'd have the logistical considerations of ... which areas they could serve, which is where the languages come in.
Of course, you wouldn't pick someone who had only been a priest for 5 years either. And you'd also want them not to be too old, to be in good health, energetic and vigorous, in order to be able to keep up with the demands of travelling for Confirmations.
Outside of those criteria, that's where the political considerations come in, and it's especially evident from the fact that Father Goldade fails the criterion above in terms of being fluent in at least two languages. In the US, where you have many Spanish-speaking immigrants, and also the US bishop would likely serve Mexico as well, and then should be relatively fluent in French not only to communicate well with SSPX leadership in general (without requiring a a translator or go-between, as well as potentially to serve the French Canadians in Quebec ... they choice of Father Goldade makes absolutely no sense. Now, with all due respect, outside of that I do not find him particularly, oh, charismatic, an outstanding homilist and speaker, etc.
Based on these considerations, the only compelling factor that remains would be that he hails from St. Mary's, is a "native son", a St. Mary's "cradle Trad" ... which insures not only his thorough indoctrination in SSPX-ism but also that he would energize the faithful at St. Mary's with the hope of limiting defections there as much as possible were Rome to excommunicate them, etc.