When somebody going is about everyday business, such as photography, there is no cause to detain them from that activity, unless they do something unlawful. Being stopped and questioned about perfectly legal activity is an affront to freedom, even though the authority was polite and professional.
If there is really a problem with photography, the laws would need to be changed to reflect that. That hasn't and likely won't happen, so in most cases there is no reasonable cause to question a photographer plying his trade.
Military installations etc. have clear instructions regarding photography, for good reasons. The bus station is fair game, at least from a public vantage place.
The patenly absurd suggestion that a guy with a big camera and tripod photographing the bus station in I'lbequirky New Mexico is doing pre production work for a terrorist organization, and the fact that there are people who are like "hey, good job for the street interrogation, I feel safer" just shows how far fear is being promoted, propagated, and exploited by government, for it's own purposes, and swallowed by the gullible, and that it has risen to the ridiculous, proves it has nothing to do with your personal safety or security.
"New post 911 world" my a$$, it's just the same stuff from clear back in the the 30's packaged in a new wrapper.