ApplicationController helper method undefined in Rails

I'm trying to write a simple helper method that checks if a user's email address contains a specific domain name. The method is needed in all my controllers and depends on the state of current_user, so I felt the best place to put it would be in my ApplicationController. Depending on the evaluation of the method on line 3, a second helper method is called. I modeled my setup on this question's answer.

When I insert this code and refresh the page, the binding.pry should be hit, indicating that the helper method I defined is being evaluated, but this doesn't happen. Instead, :disable_intercom? evaluates to true without hitting the method below. If I remove the colon, I get an error saying disable_intercom? is undefined. What am I missing here?

class ApplicationController < ActionController::Base
    protect_from_forgery with: :exception
    skip_after_action :intercom_rails_auto_include if :disable_intercom?

    private

    def disable_intercom?
        binding.pry
        if user_signed_in?
            current_user.email.split('@').include?('mysite.com') ? true : false
        else
            false
        end
    end
end

Thanks!