You should do that without further delay. No one cares about IE6.
IE6 doesn't support SNI, that means it doesn't work with a lot of websites already. Whether it works with TLS isn't really important. SNI is part of TLS.
And, I think you're mistaken that it would work with IE6, you're using a signature algorithm with SHA256 which won't work with Windows XP below service pack 3. I don't believe it's likely there's a significant number of installs with SP3 and not IE7.
But more to the point. No one cares. Most of the internet doesn't work for those guys anyway. This should demonstrate how flawed any attempt to support old clients is, security is fatally compromised to support older clients and it turns out they won't work anyway.
Using only the Mozilla 'moderate' compatibility you should be able to get A+ on SSLTEST : https://www.alpine.link/nginx-ssl-fast- ... the-class/