It means what it says, the obvious thing. I do not think any datacenter would like a customer who damages the network, like you wouldn't like to rent your house to someone who plays music loud at night.
If you get DDoSed we will not kick you out of our network and will do our best to protect you. Still, we are not a DDoS mitigation service and we don't provide any guarantee, plus we don't accept clients we are already under DDoS. We had many clients who at some point, got DDoSed but up to now, none of them was kicked out of our network.
Regarding RAID, we do run RAID 1 or RAID 5 on our nodes (depends on the setup), but that doesn't mean that damage isn't possible. Data integrity doesn't only have to do with the hard drive health, also it has to do with the database software your run, power loss, etc.
Regarding refund policy, refund is possible (and we already refund many clients when they ordered by mistake, without -for example- reading that we only offer windows or clients who never used their VPS). Crystalia is wrong regarding our refund and network policy, please next time ask.
But thanks for all of those questions, I hope my answers was clear enough.