This is the first time I've seen this claim. Where did you get this information? Was the dev playing 8 hours a day every day, or was it only a one-off thing? Additionally, was the dev doing this recently, after the delay, or was this months ago?
Secondly, even if this was true (and I do not have any evidence that it is), the developer is allowed to spend their free time however they please. The insinuation in your claim is that the dev is playing video games instead of working on the update.
Not only do we not have evidence of this, how many hours of dev work are we entitled to in a week? Is the dev required to work a full 40-hour workweek? Are we allowed to be upset if he only spends 20 hours a week making the game? Are you giving him money to compensate him for that time?
I am frustrated with the development of 1.9 as well, but we have no say over what the dev does during his free time.
I think we are all frustrated because we are waiting on the edge of our seat for an update we were told was just around the corner months ago (before the estimated release window was removed). That is upsetting, but it is important to remember why we are upset. Were you upset when the dev took a month-long break after the 1.8 release? I did not see the same critique of the dev during that time on Itch. The difference in the two scenarios was clear communication about release windows, not how much time the dev spent working every week.
You are allowed to be frustrated that the update is taking longer than expected (I am). But I have no evidence that the dev consistently spends that much time playing games. Additionally, I think the problem is not what the dev does during his free time, but that a deadline was missed.