I have two problems with this phrasing.
The first is in calling it a mistake. I think it is important that people take accountability for their decisions. A mistake is a slip of the mind. An accident. My case might be said to be a little more of a mistake due to my bipolar disorder distorting my emotions and thought process. But even so, I think it's important that we don't minimize our responsibility by calling choices "mistakes".
The second problem I have is calling it terrible. It might have terrible consequences (for all involved) due to sociogenic secondary harm, but the acts themselves are rarely terrible. Unless you are talking about actual terrible things like Danny Heinrich's abduction, molestation and murder of Jacob Wetterling. But those cases are so rare that they shape the very laws we're talking about (in extremely disproportionate, malformed ways).
I much prefer the term "bad choice" to "terrible mistake". It both shows a willingness to take accountability, without buying into the hysteria that an adolescent boy receiving a hand job is having his soul eternally murdered.
I'd also like to add another comment I shared earlier on VoA:
But I'm drifting off-topic.Part of the Pro-Reform platform and way of thinking is that it’s necessary for society to see MAPs who have offended in a different light if they are ever to see MAPs who haven’t offended differently.
If NOMAPs are seen as constantly struggling to stop themselves from doing something horrifically soul crushing, they’ll always be seen as a threat.
Putting adult-minor sexual contact (AMSC) in context, pointing out that it might be inappropriate, but it need not be the big traumatic experience that society makes, it is part of destigmatization.