Funnily enough, it looks like the site has been taken down/crashed.
Also funny to me is that it's not just sky who will be on the case here - it's also Team Kodi - and that just wouldn't be good nor clever to piss those guys off!
https://torrentfreak.com/kodi-announces-legal-action-to-smash-piracy-links-160215/
A quick view on the whois record shows its owned by Shopify;
http://whois.domaintools.com/byebyesky.com
so if I were Sky I would start off with an easy win and go after Shopify (as that would also directly damage their other hosting customers, which would immediately force them to remove all byebyesky info)
The funny thing to me is that since ditching Sky completely and saving nearly NZ$100 per month, I miss absolutely nothing of any of their channels..
I find it amazing that "cord cutters" would go and "cut the cord" and then go looking at these poor quality Kodi boxes to satisfy their viewing habits - either cut the cord properly or renew your Sky sub.
Yeah technology eh - it's a laugh!