*Notice:* I don't believe this is a bug, but I would like to bring up a
discussion about the issue.

To illustrate the matter, using `emacs -Q', please evaluate the
following snippet:

#+begin_src emacs-lisp  
  (progn
    (elisp-enable-lexical-binding 'interactive)

    (defun org-electric-pair-inhibit (char)
      (let ((pairs '(?* ?/ ?_ ?= ?~ ?+)))
        (or (when (member char pairs)
  	    (not (region-active-p)))
  	  (electric-pair-default-inhibit char))))

    (autoload #'setq-mode-local "mode-local")
    (setopt electric-pair-mode t)
    (setq-mode-local org-mode
  		   electric-pair-pairs (append
  					electric-pair-pairs
  					'((?* . ?*) (?/ . ?/)
  					  (?_ . ?_) (?= . ?=)
  					  (?~ . ?~) (?+ . ?+)))
  		   electric-pair-inhibit-predicate #'org-electric-pair-inhibit)
    (find-file "temp.org"))
#+end_src

Results in:

- The `org-electric-pair-inhibit' function is ignored, and the
  characters that should only be inserted in pairs when the region is
  active are inserted in pairs regardless.

After a bit of investigation, I found that characters listed in
`electric-pair-pairs' are always inserted in pairs unconditionally.  The
function defined in `electric-pair-inhibit-predicate' is called only for
the pairs defined in the syntax table of the corresponding major mode.

Although I believe this was a design decision, in my view, the
`electric-pair-inhibit-predicate' function should also apply to
characters in the `electric-pair-pairs' list.

I'm not sure about the implications for other use cases, but a little
change made to the `electric-pair-post-self-insert-function' solves the
issue (diff attached).

Do you think a change like this could be considered?  Thanks in advance.

-- 
Regards,
Fernando de Morais.