> The sender can look at their DNS logs to see if you’ve read your email, and the IP address of your DNS resolver at that time, which may indicate your location. [..] An attacker could look at the SNI header during the TLS negotiation
I suppose, but AFAIK no one is really doing that. So in that sense it's a "if a tree falls in the forest, but no one is around to hear it"-type issue.
And the response seems reasonable by the way; they set the correct flag. WebkitGTK has a bug and it doesn't work. It's not great, but you can't expect people to fix everything, especially for fairly minor issues like this.