I don't think it should be down to us to protect your account. If you stay safe on the internet, run virus scans and don't fall for scams that might steal passwords then you should be fine. Also it might be worth Migrating your Minecraft account if you haven't done so already. It can further protect your account as you need an email address to login and security questions to change your passwords etc.
As for the plugin itself, it's a decent idea but I haven't really seen any big problems as of yet with people having accounts taken. If it does happen it might only happen to limited amounts of people, and there's not a lot people can do (if anything) that cannot be fixed. And as said before, it is your account so it is your responsibility and if you keep it safe there will not be any reasons for problems.