Until someone at Riot says "We were hacked change your login and check your bank" these guys didn't hack sh*t.
During the time of the "attack" there were zero attacks even remotely geographically close to their servers. If it was DDoS that map would have been glowing like the sun there.
More than that Riot took the servers offline for emergency maintenance despite these guys claiming they crashed them. Can't crash a server that is already off... and if they did have access and crash them it wouldn't have taken so long to reboot them, even with a full restore from backup.
That, combined with the fact the hackers have offered literally zero proof they were in the servers at all, points to either Error# RitoTech or dormant code that was activated in which case they could not claim responsibility without some form of proof the code was even theirs or that, code having been theirs, they had anything to with getting it on the server, or activating it.
If they really were hacked Riot would have to acknowledge it. We will have to wait and see....