Well ... not to lean too heavily in the "bad consumer" territory but personally I do think there's a little bit of onus on the dev's side (not in relation to Demon Deals in particular or at all really). People may be getting this work for free but if the communication stops or production stops for no real reason, I feel like it's somewhat justified to feel like your time investment, your expectations, can get betrayed enough that it's not as black and white as "it's free so shut up." Negative feedback can be useful too if enough people are unsatisfied and it's warranted ... though clearly not to the level that guy in this thread took it, that was uncalled for.
For instance, I recently have gotten so fed up with Summertime Saga and a smaller game called Life in Woodchester that I've felt like a big fool for supporting the former (stopped a year ago, didn't feel like they deserved it anymore) and my time at all in the latter's case, feel actively betrayed by the project and seeing my hopes smashed multiple updates in a row made me wish I never even played it in the first place. Definitely not going on their forums or patreon and writing them nasty letters but if enough people feel like me maybe it's better said for the dev's sake than unsaid.