Just put 40 of your 9Ω resistors in a big long string, and it'll be fine…!
But a little more seriously, if it's just a digital on/off input, then you generally want the biggest resistors that'll deliver enough power to turn it on reliably, and a couple hundred ohms is a pretty safe bet, poking it with a generous fist full of mA… If you can get away with a pair of 1KΩ's, even better… the more resistance you can put between those wires the better.
If it's a current-dependant line (can't think of any reason why it would be), than you can probably go up or down from that a little, but will want to stick pretty close. I'd say he just picked 180Ω because it's a reasonably safe bet for inputs like that, or because he just had a whole bunch of them laying around, and they happened to work.
And, as Benta said… even better if it's already available right there on the board somewhere.