Airport police use Taser on unruly traveler, but still need help from others to control him

The situations you're suggesting would be well covered by tactical response teams. We don't need heavily armed police wandering around in the quiet airport. Putting them there might be considered foolish since any criminal considering causing trouble would take their presence into account and plan appropriately, most likely by arming themselves in the same way. It looks like the police are starting an arms race, which is not a good idea. My contention is that a radio and a hand gun are more than enough for a routine patrol in an airport. If we could only get our police here in Australia to use pepper sprays and tazers, that would be a start. But, our police here in Aussie are more and more turning to firearms as the solution to deal with every "unruly" customer.... Airports are just one of the prime examples.

We seem to have somehow moved from unruly passengers to an army of heavily armed terrorists attacking an airport.
That's what tactical response teams are for. You're talking completely hypothetically, where no significant risk of what you're suggesting exists. If you can come up with a single example of a perpetrator with an automatic weapon in a western airport, that'd be helpful. Some might also say that a hail of bullets from 2 automatic weapons might be more dangerous to the surrounding public than just one, too.
2 wandering police with automatic weapons are NOT the way to deal with large numbers of heavily armed criminals in an airport. That's not their job, at all, period, and it's not a valid reason for routine patrols to carry automatic rifles.