Replace MDM administrator with ‘malware author’ or ‘spy software’ to get your answer. There is functionally no difference between a regular company doing MDM wanting to bypass camera permission prompts and a hacker who has tricked/forced the user into enrolling into MDM.
Now, replace ‘Apple’ with ‘malware author’. What’s the difference? Well, for one, a hacker has nothing to lose and everything to gain from snooping on your webcam. Meanwhile, if Apple mishandles this permission or used it to beam video data to HQ, there’s a high likelihood hundreds of millions of dollars of iPhone or Mac customers are lost, resulting in billions of dollars in stock value loss.