No, what I trying to say is for him use Linux instead of Windows for cryptocurrencies.
While its true that linux is generally less targeted from malware, its wrong to assume its 'completely' safe.
Non-windows systems are not better secured against targeted attacks.
In fact, user damaging their system is much more probable when they are using an environment they are not used to.
Devices which are connected to the internet should never store a 'big' amount of coins, regardless of the OS.
Not only Linux is better OS and safe from any malware and viruses. Linux is not 100% that your machine is safe.
I heard that there is a way that they can hack your Linux remotely so for me Linux is not 100% safe.
The best OS for me and I know your machine is secured is Mac or Apple OS. never heard that they made antivirus to protect from any malware and viruses but i never heard their phone or macbook are infected.
I believe that this OS will be 99% safe for any malware and viruses. So if you wanted to save your bitcoin for a long time Mac OS or iPhone is a place where you can feel safe.
However, you can be still safe in linux or windows just always make sure that you add a password and change them every week or month to keep your wallet safe. Just like what I'm doing with my electrum wallet,