Some of us, believe it or not, have lives outside of geocaching. Sometimes that life takes precedence over your bug. It's not about keeping them. It's about doing other stuff that precludes, at times, logging the bugs. My friend is lucky to even log the caches he finds half the times. He does move the bugs he picks up but sometimes they're not logged correctly due to his lingering confusion about this whole logging of the bug thing. Tried to walk him through it but he's better as a hands on learner.
I lagged in moving some bugs when I got back from vacation last year. I even lost a couple bugs for a little period of time. Putting my dog to sleep and dealing with my job were more important to me than the bugs I had picked up. Sorry.
It's not about being responsible for many people. It's about life for a lot of people. Many people's lives do not revolve around this hobby.
I understand that geocaching is not everyone's main goal in life, but the issue is not someone losing the geocoins or not having the time. The issue is having the respect to message back to say what is going on. If they lost it, so be it. This person has been geocaching 22 times since then & has been on the site to log the entries, so an email would just be considerate.