I have been confirmed as well, and in my case there had been a year long phase of preparation and formally asking the Confirmees (is that a word?) whether they want to join the faith or not was even part of the ceremony. Of course there are certain non-quantifiable factors of pressure like family expectations that apply in both situation, but the option to simply refuse has always been there through every step of the process. It's possible that this is also the case for something that is so higly ritualized and has such defining implications with regards to the community as Terrigenesis.
Strictly objectively speaking, we can't rule out that this is not also the case here, as we only experience a tiny snippet of a more complex, larger process. And again, I think it's entirely unfair to judge a different culture based on contemporary, western standards. Confirmation may have that much of an impact on your social life today, but only a few generations ago, when faith played a much more defining role in everyday life, it would have been a very important part of life within the community.
As it stands, there is simply no reason to assume that Terrigenesis is not a choice for everyone involved and an informed one at that. Since it is the defining part of Inhuman culture, there may arguably some familial expectations connected to it, btu that is not reason enough to decry it as a compulsory and mandatory institution. Such is a snap decision based on false and incomplete data, the very essence of bigotry, imho.