Companies get hacked all the time and extorted with ransomware. The computers that control 3G/4G/5G network don't have data that can be held for ransom, but that doesn't mean they can't also be used for extortion after being hacked. What if they are modified to believe there are 50 phones in the space where a person's head is? The combined power output of the phone tower trying to connect to the non-existent phones would damage someone's tissues. Now the criminals can give that someone a notice that this won't stop unless they pay up or obey their orders.

If not even the giants of Silicon Valley are immune to hacking, there is no reason to expect telecom providers are either, even if public opinion thinks these for profit companies care more about public safety than money.