Last I checked, ripple's XRP had 5 validator nodes. All run by ripple.
Nope.
https://validators.ripple.com/It is not really possible to see which of these are trusting which other node, your scenario however is very likely currently (5 Ripple Inc. validators only trusting each other and others having to either follow them or completely fork away).
1. one of the "features" of ripple ledger is that it is possible to at any time for any reason, modify any account's balance, priviledges, etc. this is to protect the women and children.
Nope, this is only possible with a validly signed transaction. If something is changed without a validly signed transaction, there would be proof of that. Please give this proof, otherwise this is like the theoretic possibility that more than 21 million BTC could exist, since the protocol might be hardforked in the future.
2. The ripple protocol is not a blockchain, but a pure ledger. Now I am not any cryptographer I just write code that uses the crypto functions, but to me it seems that if the ledger is an arbitrary set of balances, then as long as all the validator nodes agree to any particular ledger, then there is no way to know if it all added up correctly.
Every ledger state has a reference to the previous state hash and all transactions that have to be applied to the previous state to reach the current state (including root hashes of a derived trie structure of them). You can know you added them up correctly if the root hash is correct.
I remember this was another "feature" as it allowed to correct divergent ledgers due to the non-guaranteed consensus. Of course, maybe there is now a method used by ripple that assures convergence and the need to edit the ledger isnt needed to keep it consistent. But it is still needed to enforce KYC and be able to freeze any account at anytime for any reason deemed valid by ripple.
Freezing only works for trust lines, not accounts and is carried out by users of the ledger (e.g. gateways), not Ripple Inc. KYC is not part of the protocol, there is only a possible way to enforce it (you can supply a list of who is allowed to hold things you issue on the ledger instead of allowing anyone to own balances of your IOU).
I don't get what you mean by "feature to correct divergent ledgers" - got any more info on that?
ripple is as much a decentralized cryptocurrency as paypal is.
XRP is as much a decentralized cryptocurrency as paypal is. Ripple on the other hand is a decentralized marketplace and settlement platform running as a blockchain with a built-in native centralized cryptocurrency.