Well, from the user who shared his bonus offer from stake.com I don't think he said anything about him being inactive
It's just a speculation.
None of us, claiming is a correct or 100% true. But, inactive account could be triggered the bonus. My friend who active on slots and suddenly not playing on Stake anymore due playing on other casino.
Got offer triggered for 25$ bonus with waggering too, in stake you can't expect a correct answer. All the things we shared is just based speculation or 2 cent from us... but is worth to tried.