Having been in a slightly similar situation (lost service dog), I can tell you that when you're actively engaged in a search, the need for different phone numbers multiplies.
My regular cell number went onto the fliers and business cards to act as a tip line. When the media picked up the story, that's the number that was publicised. It rang 5-10 times an hour, 24 hours a day.
Which made the second phone necessary. I got a bat phone to coordinate searchers with. A phone number they could call in and report their results, get new assignments, etc. A couple searchers got confused and gave this number out to the media (even though the public tip line was on all the materials). Oh well.
And then my loved ones discovered the need for yet another bat phone: this number was kept top secret, only my husband, my parents and my three best friends knew it. This was the "fuss at Grainne" line, to remind me to rest, to remind me to pick up something to eat, etc. It was also the "Grainne is about to lose it, please help" line.
I knew the search wouldn't last forever, so I didn't want to bother getting regular cells with ongoing plans. The bat phones were perfect for what we needed.
So it doesn't seem hinky to me that they needed more phones. The thing that is hinky to me is that they were keeping them secret from LE.
BTW, once my service dog was found, I topped up each of the bat phones with minutes and donated them to the local domestic violence shelter. They were much appreciated.