Be careful as the Bangladeshi government has banned bitcoin. But what if the person you have taught is the one that will report you to the authorities?
Just a scenario that could possibly happen.
I don't think the authorities really resort to such extreme measures just because someone's teaching the concept of Bitcoin, unless they could link fraudulent or large scale activities such as a mining farm.
Would be amusing to see "Man arrested for teaching friend illegal cryptocurrency without consent; friend tipped off police" on their newspaper headline

What he is teaching is banned on their country.
That's why that scenario can happen and we will never know how the authorities will take that or how they'll give punishment to this guy. But I'm not wishing that to happen if he has good cause.