The mass is not the Faith.  If so, then the indult wouldn't be a problem.  But learning, knowing and loving the Faith is our absolute responsibility and is more important than attending mass.  The Japanese, for over a century, had no mass, but they kept the Faith.  The point is, those who say the indult TLM may have very good intentions and, i'd rather have them saying the TLM than the novus ordo, but do they have the Faith?  The FULL faith?  No, their Faith is mixed with liberalism/modernism/quasi-heresy.

I'm not saying it's their fault, but it's a fact.  So, one must avoid these priests/places for the good and safety of your own soul.  We must convert them!  We must hand them literature to read so that they LEAVE new-rome and come to tradition, 100%.  The traditional liturgy, while good, does not repair or correct the modernist/heretical IDEALS which infest churches and schools run by new-rome.  A few hours a week of mass (assuming the sermon is orthodox and not tainted with sentimentalism or worse) cannot compete with 8 hrs A DAY of modernistic thinking and the protestantization of catholic living.  New rome is an occasion of sin to one's faith!  Especially their schools!

You also make a BIG assumption at an indult that 1) the priest is validly ordained, 2) that he was properly trained in the TLM, so that the mass itself isn't invalid, 3) you hope he isn't using hosts 'consecrated' at the novus ordo, when he distributes communion, 4) he's not saying mass in a church where the novus ordo takes place, therefore this chuch is not desecrated by blasphemies and sacrileges of the novus ordo.  ...if any of the above are problems, however, then the TLM is just a 'dog and pony' show and is an offense to God.