If she'd make a mess with a jar of baby food, how is she expected to deal with cottage pie, or whatever slop they serve as an "air plane meal"?
See this would be the reason why I would have thought TC might not fancy the idea.
In fairness to the OP, I can kind of see why some children would be a bit of a problem because they won't just eat baby food from a jar. DS is 7 and a half months and we are doing BLW. Not by choice. He simply won't take a spoon. Nor a pouch. And bloody hell we have tried. Plus as other people have said, infant seats are up to 2 years old and I've seen a fair number of two year olds have good appetites.
What TC SHOULD do is say what alternative food is available to purchase on the flight. That would be good customer service. Rather than simply going we can't give you another meal in a rather robotic way.
TC SHOULD be able to give a satisfactory answer to the question of why one meal per seat - even if its do to with catering contracts and space available on the plane. Or simply to say its not their policy because of the margins involved with the sales of air tickets and they are unable to make exceptions as a result of this.
TC SHOULD be able to say that an inflight meal is not appropriate for a child of this age due to its salt / sugar content.
TC SHOULD make it clear when booking that infants do not get inflight meals.
On the other hand the OP is being completely ridiculous in making such a meal out of this. sorry had to do that The OP will have to cope in other situations where she isn't at home and has to bring/purchase food for her child. It is not always practical or possible to buy a hot meal, so I fail to see why its any different.
I do think Thomas Cook are giving poor customer service, however I do think they are not obliged to provide a meal for babies if they don't want to. Its just one of those things like finding out about luggage allowance with a particular carrier that you have to swallow when you make a booking with a particular airline.
And on that note, there are many airlines which have 4 hour flights and don't provide ANY meal at all, and thousands of infants manage to fly with them on a yearly basis without starving.
YABU OP.