I was just told about this thread - so this may be old. But, I've done a lot of research into Verizon and the Sony Z3V, which has an FM chip.
TLDR: The chip is not disabled. The OS is altered to mute FM output.
I have three Sony Z3V phones. All three have an FM chip. I can check to ensure the FM chip works by using the Sony diagnostics tool. Dial *#*#7378523#*#* and you get a diagnostics menu. Select hardware tests and test the FM chip. If it was disabled, it wouldn't work. It does work. Just type in the frequency to tune to and you get radio. The problem is that this screen will timeout. When it does, the radio goes away. Also, there's no volume adjustment. It is at max volume only.
In the original OS distribution, Verizon simply didn't include an FM app with the phone. You could download one (such as Spirit FM) and listen to the radio. With the 5.1.1 update, the radio stopped working. But, there was a catch. If you used Sony's FM app - which you have to download from a "trusted source" and install as an untrusted third party app - it still worked. You could listen to the radio. Then, there was the second update to 5.1.1. Instead of "disabling" FM, Verizon went another route. They mute the FM audio. So, you can download just about any FM app. You can run it. You can tune it in. You can see that it has a signal. You can see the over-the-air identification text, which is usually the song being played. But, there is no audio.
Now, controversy: Verizon has quoted multiple times that it would cost up to $100/phone to "enable" the FM chip in the phones. The chip is enabled. They are spending effort in muting it. Verizon has also quoted multiple times that an FM tuner interferes with normal phone operations. Before the upgrade to 5.1.1, I listened to the radio on my phone all the time and never had any trouble with any other operations. In my opinion, Verizon simply wants you to use data to listen to music. They don't want you to listen to music for free.