You can also call it eMail skimming!

So no matter what the reason is, it is a fact that the email address is transferred from the plugin without consent into a database at the programmer system! Something that must be classified as questionable from the perspective of data protection.
I think, if they want to use your eMail address they have to ask for. And if they want to generate a account in your name, they have to ask for. And if they want to collect your data on their local systems… they have to ask for!