S7 Ep - what exactly was Tyrion’s logic in calling Dany impulsive?

He says it in the context of having burnt Dickon and Randall Tarly alive. The way I see it, Danaerys fought them in battle, won, gave them a choice of joining her or dying, which is completely fair.

The rules of engagement were not skewed, at least in my view. Her dragon burned people alive yes, but that’s a given, no? What did Tyrion think the dragons would be used for? If you have that sort of item in your arsenal, use it.

Most soldiers bender the knee largely out of fear. Again, this is acceptable. They were fighting on the opposing side, fear is the only thing that would make them submit. It’s far too early for those soldiers to just love Dany and want her as Queen. The two who defy her, Dickon and Randyll, are burned alive. She told them, bend the knee or be killed.

If she offered a choice between life and death, and stated it was not her intention to rape and pillage, why is it her fault or her burden if the two didn’t want to follow her? Randyll gave his reasons - fair enough - and Dany was just following through. Dickon double downed and wanted to join his father in death. That’s not Dany’s fault.

Struggling to see how she’s being impulsive so if anyone could highlight to me where my logic falls short or what I’m thinking wrongly?