> that it's a high risk for untrained individuals jumping into high intensity training

This statement erases all nuance in the real world data and experience of anyone involved in training.

You need to differentiate between one HIIT session and repeated HIIT sessions without recovery. The former doesn't cause injury in the vast majority of individuals. The latter is known to cause injuries in everyone trained or untrained.

You also need to control for what the HIIT session is. If it's spinning on a stationary bike for 2 minutes, an untrained individual generates nowhere near enough force to then injure themselves. If you're putting a set weight on a bar and asking them to shoulder press it, that's self-evidently completely different.

Yet, in your argument, they're exactly the same.