DO doesn't use SSD for RAM, only disk storage. The SSD's are local to the hypervisor, the droplets are allocated inside the hypervisor so to speak.
I believe what the support is saying is if a RAID array in the hypervisor degrades too quickly to recover normally (by replacing a single drive for example) DO will move the droplets off the hypervisor to another one.
At the end of the day, I always take responsibility for my own data security. DO's setup is very good, much more reliable than a dedicated server, but any comprehensive data integrity strategy must include steps on your side as well as they suggest.