I do not know if or why Mozilla has withdrawn the WebGL 1 extensions as I have not seen anything from them on this topic since their request (& pull request) to move them to community approved in November.
Could the vendors please clarify their intentions regarding EXT_color_buffer_half_float and WEBGL_color_buffer_float:
If there is no intent to implement them, I don't see the point of having them around. It's not clear to my why Mozilla has withdrawn their implementations. Feel free to share.