Wouldn't be the first time. Won't be the last. Corrective action applied.

I've taught both.

IME it's similar to teaching a mode uncommon in country. The majority will just go with the flow, which means dominent mode and ubiquitious thumbs. Wanting to be taught fingers and thumbs or an alternative to predominent mode is invariably only pursuant to a specific request.

I'm not rationalising the superiority of either one way or the other, but I've never had anyone find it more difficult to learn to fly with their thumbs. Of those I've taught who were determined to learn and master the pinch, they succeeded as well although on average it does seem to take a little longer to become accustomed to. ie: ie not as reflex natural, but easily enough learned through repetion and muscle rote.

As for the arguments about superiority, they're academic and rather silly contests of ego rather than related to any pragmatic reality given that 98.n% of R/C flyers are sport flyers, and IMO 80% of those wouldn't have either the skills, inclination or dedication to practise and develop them to a point where the method they used would result in any appreciable difference in visible control or performance. Failing some physical affliction preventing it, 90% of how a flyer flies happens in the head anyway. A pilot is either smooth, ahead of the aeroplane, situationally aware and anticipative or he's not. If he's not, I don't know of any thumbs or fingers & thumbs with magic tray with mandatory neckstrap or other status affording paraphenlia that will improve it in favour of a tutor or mentoring, knowledge, attitude, application and lots of repeticious practice.

Heck, at least 50% of the experienced fliers at my field still have to rediscover what rudder is.

Whilst there probably is something seemingly rational in the argument re the fingers and thumbs thing at Pro or world ranked amateur pattern level, I've neither the inclination or potential at this stage of life to go there even if I wanted to. I am btw, a thumbs only flyer, and whilst advocating neither way, they serve me well above the average in terms of observable performance. I've even managed to work out what rudder is for!

But, if you're more comfortable with fingers and thumbs, go with it and with an instructor who is at leat ambivalent about it is what I say.

FTR, the same silly arguments polarised by ego about "a wrong way and right way" persist as they have for an aeon in C/L about how to hold the handle. It's laughable. I've seen outstanding flyers conventional and southpaw hold it in all different ways with equal measure of sucess and acquitable skill. At any level, arguably including world elite. It's more about mind, application and practice than how one holds the handle or sticks.

PS: I wouldn't be surprised if somewhere in the world, someone with such a disability isn't flying R/C using the digits on their feet, and good on 'em if they can and are. Anyone ever heard of or seen such?