While you warn others not to use Blockchain wallet, you also have a change to avoid it and use a much better software wallet like electrum. Most members have already suggested and shown you how you can import the private keys to another wallet software.
Web wallet are not safe as they are prone to phishing attacks.
He would definitely do it because he already secure his keys and he can follow your advice to continue into a new wallet where he thinks safer than blockchain but there will be people that wont easily believe on his claim and would stick on using blockchain wallet because they have not experienced this problem and on top of that its also known that blockchain is one of the oldest and secure wallet that some sites and people recommends.
On the other hand there are also good alternatives and one of it is already given above. I have use electrum and I have no problems with it on the past. Nothing wrong in webwallets as long as you check the url always and do bookmarking.