Salam
Generally it's not advisable but not because infants don't have mature lungs..the lungs get mature at term (38-39 wks of gestation)..it's just that ARIs (acute respiratory tract infections) and pneumonia in newborns and infants can progress very quickly to something very serious in a very short amount of time.
And remote travel destinations usually don't have the best of healthcare facilities unfortunately.
Having said that, we did travel once with a baby onboard to Naran and lake Saif ul Malook many years ago without any issues for the baby or the mother. So it is doable but the parents just have to be extra careful.