Meh, these snakes have been handled so much that its not like handling a wild snake. As long as you don't hurt them or unduly confine/restrict their movement, they might flare out their hoods, hiss a bit and give a mock (e.g. warning) strike but they're very unlikely to actually bite. Cobras in particular telescope when they are about to bite, unless you step on them or something. That said, very unlikely is not the same as never.
You wouldn't do this with a viper. They are much faster and do not telescope their strikes nearly as much. There is a reason that these Indian snake charmers always choose cobras, even though there are a few viper species in the region.