This is interesting, and in many ways hits the nail on its head.
“National Communism” is unpalatable to many Islamics or Islamists because it tends to operate within borders and doesn’t offer strict uniformity cross-borders or nations.
“Islamic communism” or Islamism in general does not recognize country borders. It works on the basis of internationalism, so long as Islamic ideologies are embraced by anyone of any ‘nationality or country’.
Additionally, although Islamic-marxists or even secular socialists and communists actively promote an ideology of equality and diversity, they don’t practice it for themselves.
I’ve often observed communist, socialist or marxists (secular or islamic) who are primarily interested in amassing personal wealth, yet walk around dressed like a beggar on the street.
Perhaps those pushing one world government have selected Islam as their religion of choice...for the sole reason that it would give the elites more control over populations than any other religion. Of course the ruling elite would never live as devout muslims, just as the saudi princes do not, but would pretend to live thusly.