My guess is you hit a misconfigured one that redirected you to TLS without checking what host you requested.
Makes sense. I'd assume the issue is with keyserver.uz.sns.it, based on the cert I saw for uz.sns.it. I'm not able to reproduce the problem now, but I'm on a different network.
I'd recommend posting your finding to the sks-devel mailing list ... I'll post it in the morning if you like.
Please do if you think it would be helpful. Thanks Paul.