I don't know what you mean with "letting on". The census asked very directly for a probability value of successful revival.>
I mean that their actual revival estimate may be a lot higher than they are willing to acknowledge, which would explain the peace of mind.
I wrote a blog post arguing that people sign up for cryo more for peace of mind than for immortality. This suggests that cryo organizations should market towards the former desire than the latter (you can think of it as marketing to near mode rather than far mode, in Hansonian terms).
http://specterdefied.blogspot.com/2015/06/a-cryo-membership-buys-peace-of-mind.html
For those signed up already, does peace-of-mind resonate as a benefit of your membership?
If you are not a cryonics member, what would make you decide that it is a good idea?