Well' it's good for a "inside joke tweet"  for a "possible viralness" I guess, but it's definitely not right way to approach celebrity if you want their approval. I don't know what is - never approached a celebrity.

But... if I'd need to, first of all, I would be extremelly nervous. Second, I'd contact their representatives via official channels and explain about crypto in a simplest words possible and would either:
a) offer an idea or a plan (approved and supported by altcoin community) of charity, which I'd know we could do
b) offer a story of an idea or a plan of charity, which was already executed

I talk about charity like I would in some KARMA thread, something related to the tipping might be more suitable here.