I tend to agree to this gresham's law isn't that applicable for bitcoin as it talks only commodity money which on part of bitcoin isn't one of, Most probably the opposite of that will work on bitcoin. This is a non-ending discussion if both of you guys would not agree that bitcoin is only an alternative currency, just face check the reality of currencies. Ideally we can have a cryptocurrency to be used by the whole world, what's not ideal is that we are pushing it to be a non-centralized one, we are pushing too hard for bitcoin.
Well, I'm actually trying to say that Bitcoin is not a currency at all, but rother a specific non-cash asset, which is why we can apply neither Greshem's, nor Thier's law when we compare Bitcoin to a fiat currency. If we assume, however, that Bitcoin somehow becomes a currency and is widely accepted for payments on par with the fiat currency, then Thier's law comes into play and Bitcoin destroys the fiat currency (I descrided that scenario in Part 1).