Hallo everybody!
I think this is my first post, but really don't have the time for a proper introduction of myself. I'll just say that I am an adult passioned piano (and classical music) student and that I am re-learning almost everything that I have taught as a kid regarding the art of piano playing and its technique. (Irrelevant, but in my language, Greek, the words art and technique are sharing the same root...) My teacher is a certified instructor of the Alexander's Techniqe, he has study several years according to the Taubman approach, also he is an active soloist.
I travel about 7 hours in a day for our lessons

I'm getting in such a trouble, not because I want to be a soloist when I grow up, meaning in my sixtees, but because he is the only teacher -among many that had a few lessons with- that manage to relieve me from the pain in my wrists when I was playing, due to the chronic misuse of my body, previous computer-related occupation, poor posture, tension etc... But that's not all! He manage to make me fly at the keyboard with a totaly knew and unexpected feeling of security and I am standing at this magical point of my pianism, in which I imagine the sound that I want and I am able to make the necessary movements to produce it...
Well, sorry for the actually big prelude, I got excited...

The point is that now you know everything needed in order to evaluate my point of view... which is:
In deed, it is very dangerous for your hands health, thus also for your soul's

to trill with 4th-5th while holding the thumb down. You could do it with rotations, but cause of the slave-finger, the thumb, you need double rotations. Rotations are not a simple concept, cause you have to rotate your hall arm, meaning to find your axis, to have basic knowledge of your bones, their joints and their allowed movements etc. Double rotations are more difficult to achieve... So, it's not a technique that you could learn on the spot, not even for Beethoven's sake...

My opinion is that your hands' happiness is more important than to play the score exactly as it is written and that the performance of a piece is judging by the >>>overall<<< sounds and the sonar atmosphere that the pianist creates - or fails to create... not by a trill. After all, you can cheat, by playing a little bit more forte -not more brutal

- the thumb, so the note will sustain a little longer and enough for the time that trill's overtones will cover its absence! After all, we, as pianists, ought to create illusions!
My best wishes for your progress, your hand and your... trills and excuse me for the embezzlement of your post!