Let's not hypothesize about Apple's response.
Apple participates actively in the WebGL working group, and has made strides to improve their WebGL support in recent months - integrating ANGLE to provide WebGL-compatible OpenGL ES 2.0 and 3.0 semantics, to be able to support WebGL 2.0. Google is collaborating actively with Apple on these efforts.
If you have concrete test cases that show either compatibility or performance issues on any WebGL implementation, please file a bug about it, either on the https://github.com/KhronosGroup/WebGL
issue tracker or on the browser's bug database directly. It is most helpful, and greatly appreciated, to contribute a conformance test to https://github.com/KhronosGroup/WebGL
for compatibility issues that aren't already caught by the suite; for performance issues, feel free to contribute a sample under sdk/tests/extra/ which demonstrates it.
Sketchfab, Shadertoy and many other WebGL sites work beautifully on iOS, and I am hopeful that WebGL 2.0 will be universally deployed everywhere, providing a good baseline of graphics functionality on the web.