I can't speak for dji, but when I was designing antennas, I didn't get them working in free space, and just throw them into the installation and ship.
A plastic with a dielectric constant of ~ 2.7 - 3.5 that close to the radiating element can detune the antenna V.S.W.R. in a major way, so the antenna must be designed to work with the structure. In this case, removing the antenna from the structure it was designed for can actually detune it in the same way.
You may be actually hurting the performance by moving it.
Now, having said all that, I'll bet dji did exactly the former.
They probably designed a simple sleeve dipole tuned for free space, stuck it into the skid strut, and let it go at that.
You may indeed get some benefit from unsheathing the antenna, but perhaps no more than 1/4 to 1/2 db with pattern ripple in a 270° arc away from the skid strut. Inversely, there may actually be more shadowing in the direction of the strut. You also have the other 3 struts, the skids, and multipath from the camera/gimbal to deal with.
I doubt that real world testing would show any discernible or repeatable results.
A better exercise might be to extend the antenna lead and let it dangle an inch or so below the whole mess. Now there is an unobstructed 360° view.
Not so great for longevity, though. ;-)