Make field settings enable in the "manage fields" tab to use PM module more effectively

Problem/Motivation

The module should give you access to manage fields to use the entity reference view. But unfortunately the "manage fields" settings are disabled. If this area was open; Integration with other modules such as views, flags, different form options can be easily achieved.
For example, using "Views: Filter by an entity reference view".
"Sending messages only to followers" restriction feature can be used by using "Views: Filter by an entity reference view" instead of the default through the member settings in the manage fields section. Or many more features depending on your creativity.

Any idea please, thanks.