Even if you can 'see' colours etc -- I have a non-theory, because it's not even a theory that -- there's no such thing as being able to use 'colours' to assemble (create) the 'western' style of music - or related style. At least, it's not going to be like --- I'll blend this colour with this one, and we'll get a chord pattern etc out of it .... with arpeggios, and scales, or counterpoint etc.
It's plausible that people really might get colours for pitches popping up in their minds - for eg. each note. And then there becomes the 'consideration' of --- is it 88 different colours (assuming 88 keys of standard/regular piano) - and will they then map each of those colours to a key of the piano. And even if they do have 1 of 88 colours in their mind, then there becomes the consideration of sequencing those colours - when playing. So it's still going to be memory work of some sort. And this also leads to the question of - after maybe future interviews with those people will get answers for -- what benefit do the 'colours' provide in their music?
As in - what benefit will colour patterns have over people that already have non-colour musical notes (pitches and music) in their minds? I can understand that perfect/absolute pitch will allow a certain benefit of translating pitch-in-mind to key-on-keyboard very directly and immediately.
Another consideration will be - whether it's 88 colours, or is it a group of 12 colours, C, C#, D, E through to B.
And piano notes aren't 'one dimensional'. There is also attack, decay, loud, soft, nuances, timbre etc etc etc. So a 'colour' is probably not going to cut it for music creating or generation - and this is referring to say 'western' style music that is. So - a study - or interviews will hopefully establish some details about what the 'colours' will do.
Interestingly - if theorists, and maths etc folks can develop a theory that ties colour blending to form practical/useable equivalent to chords and key signature, and existing music theory related areas, then that will be very interesting.
But then - it is also known (I think) that the colour-seeing piano players and musicians don't all see the 'same' colours.
So there's going to be work and time involved to seeing what's going on in that area --- what it is all about that is. It will mean people writing down how they apply the seeing of colours to the area of outputting 'music'. As in ... how it fits in ... aside from perfect/absolute pitch benefit.
Absolute/perfect pitch certainly allows people to get finger on key faster ..... without needing to go down the relative pitch and intervals/aural training path. So the non-theory ... or theory might be just be in the benefit of mapping pitch to note on piano. After pitch of heard note translates to a colour in mind, and after associating each of 12 colours to the particular notes of a keyboard ... the colour-seeing absolute/perfect pitch person will have the benefit of getting pitch to keyboard very conveniently. But once again, well-trained relative-pitch people can get by very well too ... but may require occasional reference pitch for calibration.
It is known that some people do lose absolute/perfect pitch ability with age, requiring switching to relative pitch.