Delaying “solid foods”

Is it normal to postpone offering purées and soft food I’m babies that were born premature? My sister had her baby on December 2023. His actual due date was the first week of February 2024. He is now almost 9 months and she still isn’t offering purées or anything like that. Only formal. Is this normal or something that others have dealt with? I’m not judging her or anything this is just the first time I have heard of postponing for this long. She said she isn’t planning to start purées for another couple of months because “He was born 2 months early, so he is delayed by 2 months” basically explaining how he should only be almost 7 months so she should only be treating him as a 7 month old.

I do want to state there is nothing about this baby that would even suggest in the slightest that he was born prematurely. He has met and exceeded all of the medical health percentiles for a baby that was born at a normal gestation. His providers have all stated he is doing phenomenal all things considered.