What comes to conformance, you should refer to latest OpenGL spec (now being
4.6). In this case you want to render to RGB32F we should take a look at
section  "9.2.5 Required Renderbuffer Formats". Since you are using a sized
format, it means you need to check if driver is required to support this from
column 'Req. rend" as said in 9.2.5.

That said, IMO this bug should be considered a feature request (which is fine)
rather than a missing feature.