Actually you can feed solids at 4 months
with my daughter because she was drinking 80oz a day at 3 month my dr told me to start her on solids if she could sit upright for long periods of time, they usually tell you not to put cereal/food in the bottle but they have special nipple now that you can do that with.
I wouldnt worry to it every other baby is the exception some babys just need more food and trust me its so much easier to probally feed a baby in a bottle at that age than trying to find a high chair that doesnt fit your baby and have them spit food all over the place!
I think they just worry about the choking factor and that is why they dont want you to put food in the bottle but some moms are allright with that I guess.