I don't think you're being extreme to not go. A lot depends upon the situation (i.e. who is getting married, what type of church it is, how looney the priest is, etc).
Logically, if one believes that the novus ordo is wrong and/or a sacrilege and/or promotes "abuses" (i.e. promotes an atmosphere of sacrilege) then it is not extreme to say that going to an "indult" "mass" is indirectly condoning the novus ordo, and by extension, its related sacrileges. For the "indult" priest and laity, by definition, say that they agree with the novus ordo, they just PREFER the latin.
Now, there is a lot of gray area in all this, as others pointed out in earlier posts, related to family situations, conflict, etc. But putting all this aside, if you go to an indult, you are affirming its significance, to some degree.
May God have mercy on all of us as we wade through these crazy theological times!