Who gets the throw-in if the umpire cannot make a decision?

Once during a game recently, one of our umpires didn't see the last player touching the ball when it went out of court at the goal line, so she couldn't decide which team should be awarded the throw-in. However, after some "persuasion" from a player she allowed herself to give it to one of the teams (for the sake of continuing play).

This happens rarely but is not the proper way to handle the situation. Rule 18.5.1 (iii) says:

"A Toss Up is taken when opposing players are involved and the Umpire is unable to determine the last player to touch the ball before it goes out of Court."

The correct decision is therefore to conduct a toss up. The better one gets as an umpire, the less often one will have to use this option...