I think it’s just that the bacteria in the hotter container woke up to a warmer, nicer environment. Warm temperatures are much better for bacterial growth. While it was too hot they didn’t seem to care at all since their spores protect them completely from damage.

Agreed - I really enjoyed the writing. I'd have normally skimmed for the conclusion but ended up reading it all. Shame that that's so rare these days.

They could have some coating that make them stick to the content of the tea bag, basically affecting their solubility.

Perhaps just random variation? They only did one plate, after all.