Complete scam, and not an original one at that.
Yes, there will be a 6 year old somewhere, but this whole scenario has been created by the parent , and the letter written by the parent/parents.
Social media is full of this. The most common ones are a girl playing a boys sport and getting ' bullied' , so the parent does a social media post saying how proud they are of them. Cue offers of kits, days out etc from brands and organisations looking to raise their community profile. See also a slightly overweight child playing sport, a boy doing drama..that kind of thing.
Kids with signs asking for players shirts at sporting events also gets my spider senses tingling..I think a lot go straight on ebay, and it's a practice encouraged by parents again.