It's evidently not 'expected' behaviour from the point of view of the user. Just because you happen to put an email address in the title of a calendar event doesn't imply that I expect the software to go and send messages on my behalf.
A proper way to do it is, Title: "Email Alice", Description: "alice@example.com".
You can't change the behaviour of users, but you can make your software easier to use and more predictable in its behaviour.
At present there's no way to predict the behavior until after the fact. Something with that much consequence (sending an email to an unintended recipient) should never be done silently. By all means take the initiative with autofill etc, but the user should have the final say.
If the supposed design revolution within Google (http://www.fastcodesign.com/3016268/google-the-redesign) isn't just for show, the Calendar team (assuming there even is an ongoing team) clearly hasn't been touched by it and that ought to be corrected.
Generally, I thought Google hired smarter people than you seem to be, so possibly you're some sort of false-flag bullshit.