Why is it wrong to write things down, so that they can be handled later at the appropriate time?

When the time is appropriate, how will we find them all?
I tend to forget things, if I don't write them down. I also appreciate (in my work) knowing what may be needed in the future.

Then YOU write them down, and YOU keep them, - until the time is appropriate.
I have also experienced, quite frequently from "support", the comment that "you should have mentioned this sooner -- it's entirely too late to change that now".

Then mention it, but when the time and place is appropriate.
And I really thought we were asked to test and comment - not test and forget.

Yes we were. But an experienced tester would know when his repeated comments could be seen to be counterproductive.
Finally, why are comments on the number of crystals, or the movement speed of the fan coral, or the movement type of the hands of the clock, more acceptable than comments about the settings panel? [Otherwise, please talk to those folks, too]

I
have personally commented myself on all those, - at the appropriate time and place.
However, I am quite willing to follow the author's wishes.

Good.