ExSimGuy
What I presume he means is the same as I said. That it is the Police officers decision to require a breath test from a pilot. Once that requirement is made, the legislation says that it must be taken at the place of request or nearby. But that is the officers decision to make not the person required to take the test.
So, if the officer decides that he is going to administer it at the doors of the aircraft, thats where you take it. If a pilot (or anyone else covered by this legislation) doesn't take it, then he faces either arrest or summons for refusal.
As The Nr Fairy points out it is preferable to do it out of sight, but it is not compulsory. Trying to put a condition on where it will, or will not be taken will only annoy the person you really do not want to annoy.
Drivers are in the same position. As a police officer having had an accident, I was required to take a breath test, no problem with it, hadn't had a drink in days, but it was conducted in full view of the public. I wasn't impressed, and no doubt the public thought I had been a naughty boy. But at the end of the day, did it matter? No.