Options aren't what they used to be when we were at school, nor when I was teaching and going through similar discussions with my y9s at this time of year. ( I'm retired now)
Schools are now judged on their progress 8 points. An overly complex scheme of awarding points for gcse passes obtained in which some subjects carry more weight than others. Children tend to get lost and forgotten in some of this. This is why geography, history, an mfl, computer studies etc. figure on so many options lists.
Schools cannot afford to have pupil centred options as some did in the past, they all have to have an eye on results 2 years in the future.
Your son is a bright lad - he's doing triple science. All being well he'll get enough points from the GCSEs he's selected to go onto A level etc etc.
He wants to do this - let him. It'll be useful in life. But neither will it bar him from other areas of future study. Universities tend to be more concerned with A level subjects than GCSE ones.
He's a lot of academic/bookish subjects and a more practical one, which is his choice, will give him a good balance.
True is traditionally a 'girls' subject. And.....
I often had to sort out y10 problems pupils who had fallen out of love withn options choice. "So why did you pick it then?" "My parents made me" was a common response.
I suspect he'll be happier doing this subject as.... A: he's chosen it, B: you've supported him in this. ( given that you do)
This happiness will likely result in a pupils that will do better all round.
CP
( personally I think this is one of the things that they should all do as well as first aid, financial education etc - but that my hobby horse)