Any product or service can be used for evil by evil people.
I've used Myles' service. It works amazingly well. So well, in fact, we looked at using his API to integrate the functionality into Socialyzer. We ended up not coming to terms and we built some scripts to do this for ourselves internally.
We use this functionality to build a very targeted following of people who may find our service (http://www.rewardrkt.com) useful . Our conversation rates from favorite, to follow, to registration on our site are extremely high. The people we auto-favorite are finding value in what we offer.
Favoriting their tweets is an efficient way to "introduce" yourself to someone without being super pushy.
After Twitter shutting down Flattr I reached out to Myles again to see if he'd seen the news. Of course he had, and I see his blog post as a bold move. Why wait around for doomsday if you can either (1) make it go away or (2) bring it about faster and move on to the next thing afterward.