It will take ages to brute force a good password while there is no other way to open a crypto container.
I think it is quite naive to assume that your security protection will never be broken, especially as far as sending out a public link and encouraging people to hack it. Who knows, people might use other means to get your funds or employ tactics. There is a reason why people suggest offline backups if you want to protect your money.
When he said about having wallet offline and backup online, I read it with alot of confusion and skepticism. Then act reacted to it and I was waiting patiently for him to reply and now he has given his response about using a crypto container and unbrute-forceable password.
I can maintain that whatever security you are using, as long as it is online, it is vulnerable. When mixin safe was hacked it gave me a re-assurance of my belief.
The best way to secure your seed phrase is to make sure that no one has an idea of where it is saved. The moment you think it is unhackable and point public eyes to it, you would be taken by surprise.