All current research I"m aware of says there is no benefit to static stretching before exercise and there may be risk of microtears if stretching cold muscles.
Most aikido dojos seem to do a hodgepodge of range of motion, static stretching and dynamic stretching as their "warmups." I believe that good range of motion is all that is really needed. Nobody listens to me :-)
I'm sure your research is well-founded for sports and activities that emphasis the use of regular muscle-power. I wonder why one would want to warm up conventional muscles for use in aikido anyway.
As I understand it, a lot of aikido stretching comes from the makko-ho
and nishishiki undo
. Then there's chinkon no gyo
and other solo exercises.
The way I see it, they are part of the conditioning rather than working on external muscles to prepare them for use in training. In my experience,even push-ups tend to be adapted for conditioning wrists, knuckles and so on with conventional fitness being a useful byproduct.