President Obama is asking Congress to pass a bill that keeps people on the No Fly list from owning guns. Politicians frequently find the need to say or do anything to make it appear to their supporters that they are taking action. But I don't think Obama actually wants this law, and he wouldn't ask for this law if he actually expected Congress to pass it.
This is how the No Fly List is supposed to work. There are roughly 47,000 names on a secret list, and the only way to find out if you are on the list is to buy a ticket and try to board a plane. The government does not want people to know if they are on the No Fly List.
I can understand the reason for this secrecy, even if I don't agree with it. If the government thinks that someone is a sleeper agent, they don't want that person to know about their suspicions. Maybe they can't locate this person to arrest them, or maybe they want to see who he's talking to before they actually collar him. My own thought is that if the government has probably cause to think that someone plans to kill a bunch of people, they should arrest him if possible or at least let the public know that person poses a threat.
But as long as the list is secret, terrorists have a strong interest in knowing if they are on the list. So if a terror group is planning a major operation and wants to know which of their assets in the US can actually board a plane, the group's leader could simply order his followers to try and buy guns. Whoever successfully buys a gun is not on the No Fly List, and whoever can't buy a gun would resort to Plan B.
If the terror-watch list was available as a publicly searchable database, then terror suspects would have difficulty buying anything that required them to show ID. But if the government wants to keep people from knowing that they are being investigated, then even terror suspects should be allowed to buy guns, as absurd as that sounds.
A less absurd solution would be to issue arrest warrants for people with known terrorist ties. After all, if a person is too dangerous to be allowed to fly, they are too dangerous to be allowed to drive, board a train, visit a museum, or buy chewing gum.