One general example of why openmpi shouldn't be creating
shared libraries with undefined environ symbols is as follows.
If a python based application was using the openmpi shared libraries
linked into the application's python module, your suggested
approach would be unusable since the user would have to rebuild
python to explicitly provide the missing environ symbol. You
will always run into such corner cases as long as openmpi is
misbuilt on darwin.
ps I have posted this issue to Apple's radar bug reporter
as issue 5233061 as well.