I think that using ProtonMail Bridge defeats the purpose of using ProtonMail in the first place. At this point there is no real difference to other hosts, except that the emails themselves are encrypted on ProtonMail's servers.

Now you are using another email client that you have to take care of its security yourself, and besides, anyone who has access to your machine will have access to your email when you turn on Bridge and open your email client. A big part of Protonmail is that these emails are not "stored" (cached, whatever) on your machine.