In my experience, even the best Android drivers just took locks when using OpenGL from multiple threads, even for resource creation, so it's sort of moot.
From a hardware perspective just about every Android SoC minus a few odd ones have unified memory so there's really no reason for them to take a lock, at least for the heavy part of the operations that copy the texture and tile/swizzle.
All those users will leave you a one star review when it crashes on their device.