Quantum computers will make the current generation of bitcoin addresses obsolete within the next 5-10 years. So the funds you are trying to give your child will be stolen before they can ever be spent.
That's if the input of his timelocked transaction has its public key exposed.
Otherwise, it could still be safe.
But given that the intended locktime is 14 years, it's hard to conclude what will be the situation with QC and the current script types.
e.g.: It may be able to immediately steal just-broadcasted transactions from non-QC resistant scripts in 14 years / the script type used by OP could be consensus-invalid by that time, etc.