Every since they made "do no evil" their position, it seems that evil has been redefined from "profoundly immoral and malevolent" to "anything I don't really like, even if it only slightly harms someone else's position".
Google is supposedly hiding a direct competitor to one of its main product from its search engine, the main entry of the Internet for millions of people that aren't very proficient with computers.
Google's product, Gmail offer considerably lower security and privacy than this competitor and using it instead of ProtonMail may very realistically get someone (a journalist, whistleblower, LGBT activist...) in deep trouble or even killed in lots of places and contexts.
I think this is a pretty evil move. Not only for this but what it represents when, again, millions of people were educated for years to enter the Internet through this search engine and don't have any clue that it may not only tamper with the order of the results but also hide websites.
If you are using ProtonMail for anything critical you're doing it wrong. It might be more convenient than other encrypted mail solutions, but it's in-browser cryptography with all the security issues that entails.
Sure it is not the best tool -- but depending on what means "critical" in your context it provides great security. Not against the NSA targeted attacks, sure, but if you're not so concerned about your adversary using exploits and more sophisticated tools (versus just demanding data from the provider or something like that) ProtonMail goes a long way.
Anyway it is, for most cases I can think of, much better than Gmail.
