If TSA wants to "secure" people I don't think they need evil magic robot doors to do that. But because this is HN, of course, I can't win that argument.
I would argue that TSA agents are more likely to abuse their power while benefiting from a power imbalance. Stopping someone physically is much harder than locking them in a box they have to walk through to get out of a terminal.
I don't believe you can't win the argument because this is Hacker News; you can't win the argument because of the TSA's track record (and to a greater extent, the results of unchecked power on humans).
I'm absolutely sure the TSA wouldn't abuse this device. At all.