Modern brushless gimbals actually deliver really good stabilization - probably not as perfect as this and maybe not good enough to carry a Red, but take a look at this for what is possible with a GoPro: https://www.youtube.com/watch?v=ch2iRCWZfKc
Seems like it could be adapted for lightweight telescopic optics.
What makes you think it isn't already?
The article below the video, that clearly shows the system mounted on a full-size helicopter.
I think the implication was that the military (or drone hobbyists) likely already have similar tech on their UAV platforms. Though maybe not capable of 4K.