FIPS restrictions are not as comprehensive as one might infer from the documentation
doc/cha-internals.texi#L691 has the following claim:
When the FIPS140-2 mode is enabled, The operation of the library is in addition modified as follows.
- Only approved by FIPS140-2 algorithms are enabled
As far as I understand, this is mostly true, as in, ciphers and MACs usage is restricted, but not, e.g., curve selection. But the doc text might leave the impression that the imposted restrictions are comprehensive.
I suppose that either the wording should be amended to clarify the extent of the restrictions in place, or the library behaviour should be extended to restrict more of its functionality when in FIPS mode.