It's in this subreddit somewhere. A Venezuelan talked about how he's "not a gold farmer, but knows them" . They're getting better at going undetected and that's one of the ways.
The bot isn't programmed itself to log during peak player times, you set the times yourself. The breaking system is very common in bots.
It doesn't matter if Jagex counts the player as a bot or player. All that matters is the player count number. If bots are logging out for peak times, then this would explain why we have low peak numbers as well.
It's still far from indisputable that player count is decreasing based on the terms you used. If there weren't any bots at all, or Jagex released stats showing how the player count is affected after bots are banned, and it correlates with what you said, then you could say it's indisputable. I'm not saying you're for sure wrong or I'm for sure right because there is no possible way to say 100% either of us are right.