This privilege is to be understood in such a sense, that it bestows the faculty to say Holy Mass anywhere in a decent and respectable place, and on a consecrated altar stone, not, however, on the ocean.
Does every home that receives a priest for mass have an altar stone? Do the priests bring it with them?
It seems to me this is another problem.
Our Resistance chapel has a properly consecrated altar stone, and prior to that, properly blessed Greek corporals with the relics of traditionally consecrated saints sewn into them (I know, because I personally procured the relics directly from Rome, and they were then transferred by an Avrille Dominican from their containers into the antimensium).
On another note, if priests should generally not say Mass in a church of another Rite, then trad priests should not say Mass in any church built for the Novus Ordo )as in done in many indult locations).
Yes, I understand that the fiction of “two usages -ordinary and extraordinary- for one Rite” would seem to bypass the preclusion, but we all know that is nonsense:
A Rite which departs from the theology of the Mass as defined at Trent is a whole new concoction, not another usage of the same Rite (as one could argue for, say, the Dominican or Praemonstratention Rite).