Did you read the text at the bottom of the post? They are randomly installing malware on users' devices to break or harm or otherwise self-destruct when Cellebrite machines read them.
I'm not speaking for myself. I would opt in personally. I'm speaking for my mother who just wants a secure and reliable line of communication with her son without being pulled into some offensive scheme that could land HER in trouble or cause damages.
If something is broken or destroyed without user knowledge or understanding or consent, you better believe Signal will see court cases.
It's entirely possible that I'm wrong and this will cause your phone to explode, but if you don't trust the Signal developers enough to assume they won't intentionally explode your phone, you probably shouldn't be using their product.