Communication Devices During Alliance Selections?

[XaulZan11]

At the Wisconsin regional, our team representative asked if he could use his cell phone to text during alliance selection to communicate with us scouts and was told yes. As the 5th seed, our backup plan was to write the team number of the teams to pick on a whiteboard. We were picked by the 2nd alliance. When it was our alliance's time to pick our third partner, he took out his phone to text who our partner wanted to pick to get our approval. He was told by the MC that he needed to put his phone away. I was unware there was such rule and still cannot find it. Perhaps I just didn't look in the right place. Is this a legit rule?

In the end it worked out well as we got a strong 3rd partner, but it looked bad having him trying to communicate with hand signals when we had a system in place.