To be fair, she’s a children’s doctor and will see many more children than most of the people telling her stories about their own kids. She’ll know if he is showing other signs of delay. So I think that’s fair enough that she’s told people to shut it.
The real question is why she shows so much of her children online that she has to stop showing one of them because of delays - surely would be more sensitive to just stop showing all the kids. It really won’t be long before her kids grow up enough to be so embarrassed by the things she’s put up of them as toddlers