Can we ban ripple? Yes
Are we going to? No
Salty, this answer is succinct, to the point, understandable. It's also quite terse. Can you weigh in a bit more about your motivation? Or some of the ideas posted about providing ripple with it's own subforum or moving it to alts?
As far as its classification, Ripple it is not technically a cryptocurrency, but it is close enough to stay in the Alt Currencies section. Adding new subforums is not done unless it is completely necessary. Unnecessary subdivision makes the forum clunky and cumbersome. It would be like adding an Amazon section for all things having to do with Amazon, an Ebay section, etc. Eventually it would take 30 minutes just to navigate to subforums.
As far as not banning it, we don't ban anything unless it is completely necessary. Censoring technology is a good way to retard growth in related fields. Alt coins explore different options in cryptocurrencies, ripple is another system thats out there doing whatever it is doing. As this is a Bitcoin forum, we won't especially cater to Alt Coins or Ripple, but we will give them the basic courtesy of allowing discussion of them in their own out of the way section (Alt Currencies). I don't care one way or another for ripple, but I think its just fair to let it run its course. Paypal deals in fiat and is a central company, censoring Paypal would be far more appropriate than censoring Ripple, as they have even less to do with the central Bitcoin theme of the forum.
In short, we don't ban/censor anything that doesn't by all accounts need to be banned. The only things that are banned here (that I can think of)
1) Anything illegal in the OP's jurisdiction, baring completely unreasonable laws. If it is illegal to sell your used socks in your country, we probably don't care here.
2) Death threats
3) Spam
The only Alt Coin or anything similar that was ever banned (temporarily) was Scrypt Bitcoin just called Bitcoin but using the Scrypt algorithm. That was because I received a warning from the developer that downloading (Scrypt) Bitcoin could overwrite Bitcoin wallet data if you installed it because they had the same name. That was later tested and found to be untrue, so it was unbanned.