Are you sure it's a lie?
You bring up an interesting point.
However, and its very late so I don't remember
all of my logic lessons from high school mathematics off-hand, there's a Theorem of The Gullible Child or... as intellectual wags later somewhat cynically dubbed it
Webster's Law:
The more a child believes something an adult has told them, the better the chances are that this fact was completely made up.
Since Phillipe not only believed Teodor but believed him so much that his entire demeanor did a 180, it can be assumed that the odds are very likely that it is a total fabrication.
When you tell a child, for example, that all the toys were bought by Mommy and Daddy working very hard, they were the fruits of the endless humiliation and suffering that is Earning Money, a child's just not gonna believe it. A child wants to be happy, you understand, it is its natural state, its not gonna handle very well that this GI Joe Thunderclap playset that brings them such job is actually the byproduct of something that makes Daddy occasionally look whistfully over the edges of very high buildings. It cannot be so.
Tell them a morbidly obese immortal who can shapeshift down chimneys and travel faster than the speed of light gave them the toy
because they're so special and they will buy that until nearly puberty.
Why do I lose teeth, a child asks. A child does not really understand death, you cannot tell a child "Well, this is nature's way of telling you that a chunk of your life, the easiest chunk of life, is gone now. Hormonal confusion and hard labour await, quickly followed by the swift dreamless abyss of unbeing."
If you tell her it is so a winged imp can give her a small amount of money, bingo. It is accepted.
When you tell a child that the divorce had nothing to do with them, it was that mommy and daddy aren't just getting along, bingo, it is accepted. There are all sorts of examples like this throughout history.
Webster's Law.
And the fact that Phillipe's 180 was accepted in such a rough and tumble "well, golllllly, you're right!" sort of way "gosh, he's a good egg, that couch" in the manner of a shoeshine boy who believed that he was left a crappy tip, only to find out it was an amazing tip? This just cinches the deal.
It is called
The Buckaroo Corollary.