You believe that if the user has expressed the preference to have links opened in the same window it’s more polite not to do what they have expressly indicated?
People who use screen readers are the ones most inconvenienced by opening things in new tabs when they don’t expect it. That’s why it’s generally recommended not to hijack links into a new tab (even though it’s what you and I prefer).
You can change the user default preference to open in a new tab, and also apply that setting to all users. That will allow your site to be more polite without violating the user preferences.