I've heard of DDoS attacks used to divert the admins attention while a real attack is occurring. Also I know packet flooding can cause some network hardware to switch into a lower security mode in an attempt to handle the load. I'm not sure if either of those apply in this case, though. I definitely am not a network or security expert.
Right, they're used as distractions fairly often. The rest of the explanation makes no sense though; that is, I don't see how the DDoS would then "make the system vulnerable" to Bitcoin theft. Unless it was something like where the attackers already had access, but most everything was kept in cold storage and they wanted to force them to move a lot of BTC into their live wallets.
