There are a few things to consider about Answergy, cause I'm familiar with the "phenomena". I'm tagging it like this, because there were a few conversations on social media about Q&A sites. Wanted to build a few myself, but I've given up the idea at some point because I've concluded their success is based on their links, not on the Q&A format.
1. That wasn't a classic redirection made for "juice"-gain, that was a full-redirected migration.
2. The initial website is in the same category with several other Q&A websites that suffered a huge blow in the past few weeks, and probably had a manual penalty.
3. Check-out the backlink profile of the initial site. I didn't analyze it, but if it falls in the same Q&A category of successful websites, should have a ton of hacked links/niche edits.
They've done it to avoid the manual penalty triggered by their backlink profile. This method didn't seem to work for a while now, but if it grows consistently in the following months, it's probably working again.