The domain move which protonmail did looks quite risky: Country TLD to generic domain, new domain parked at Godaddy before and the first owner of this domain run an email server which maybe did unexpectedly closed shop. The domain move happened at the same time when protonmail vanished from the search results.

Instead of publicly looking for a scapegoat for their mistake they should tell readers of their blog the one lesson to be learned from this story: Never use a country TLD for something targeting more then this country!