I do not think any of the existing libraries handle it. One option is fixed in simplejson and submit a patch to the authors. Another option is to fix in gluon.serializers. A third option is to fix in the jsonp view (as the article suggests).
The best option would be to have this fixed by simplejson/json, however, I don't think they will accept it, because this is not a specific json encode/decode issue, unless they want to add the feature to catch the bad javascript. I think web2py should handle this instead.
Wouldn't be better to prevent users from using those characters in json input? (not a rhetorical question)