The transition parliament voted in April 2015 a new electoral code that had a new clause (that read as if written by a 20 year old) excluding persons from running for office who had supported modification of Article 37 of the constitution that limited the presidential term.  President Compaoré was ousted in October 31 2014 precisely because of his, and his party’s (CDP), plan to change the constitutional and permit him to legally run for office again.  An ECOWAS court ruled in late July against the transition parliament’s change to the electoral code.   But the transition government decided to ignore the ECOWAS decision.  The Constitutional Council ruled that specific individuals could be excluded from the election. So in late September the CDP candidate for president Eddie Komboigo and former foreign minister Djibril Bassolé (running under the banner of a new party, Nouvelle alliance du Faso (NAFA)) were excluded.  A few weeks earlier, CDP candidates for the legislature had been excluded.

The coup leaders today apparently cited this exclusion as the main justification for the coup.  The coup leader Gilbert Diendéré is closely tied to the CDP: he has been a close ally of ex-President Compaoré, his wife was second on the CDP national list for the chamber of deputies in the October election.

But I think the coup would have been organized regardless of the exclusion of CDP candidates.  For three reasons:

1. I think Komboigo or Bassolet winning was likely to be a low-probability event.  There might have been a run-off, and they might have been able to pick off Roch or Zeph.  But seems pretty unlikely.  Seems more likely that Roch or Zeph would have joined together.
2. The transition was likely to try to restructure the RSP regardless as a last act before the election, and that would have been perfectly legal under the transition authority. That certainly would have provoked a coup.
3. If the CDP did not win the election, judicial inquiries into the killings of Thomas Sankara and Norbert Zongo and possibly others would have proceeded, and Gilbert Diendéré and others from the RSP would have been implicated.