Here are a few examples where platforms discuss emergency requests. It would seem once the Amber Alert was triggered, that would support these scenarios. However that is only my opinion. I am not sure what the turn around time would be in an emergency classification, or if it would cover all user content, etc.
Google fine print:
If we reasonably believe that we can prevent someone from dying or from suffering serious physical harm, we may provide information to a government agency — for example, in the case of bomb threats, school shootings, kidnappings, suicide prevention, and missing persons cases. We still consider these requests in light of applicable laws and our policies.
https://policies.google.com/terms/information-requests?hl=en-US
Facebook Emergency Request:
Emergency requests
In responding to a matter involving imminent harm to a child or risk of death or serious physical injury to any person and requiring disclosure of information without delay, a law enforcement official may submit a request through the
Law Enforcement Online Request System. Note: We will not review or respond to requests submitted by non-law enforcement officials. Users aware of an emergency situation should immediately and directly contact local law enforcement officials.
Safety Center
TikTok Emergency Request:
Q: What type of scenarios would constitute an emergency?
All emergency disclosure requests undergo a case-by-case assessment and each request will be evaluated by our law enforcement response team based on its particular circumstances. However, the following are some examples that may constitute an emergency:
- Cases of child safety and exploitation;
- Missing persons;
- Suicide and self-injury scenarios;
- Imminent threats of violence; or
- Natural or man-made disaster situations (such as fires, floods, earthquakes, etc)
https://www.tiktok.com/legal/law-enforcement?lang=en