Pinoyme,
I'd disagree with your first statement that MacArthur's antipathy towards the Huks contributed greatly to the start of the Huk Rebellion.

I think that the basic motivating factor behind what became the Huk movement was the changing nature of the tenancy system in Central Luzon -- traditional relationships between tenants and their hacenderos broke down over the issue of non-contractual benefits as the Philippines began to modernize governmentally and legally under American control, and the firm grip the landowning class had on most organs of government and the courts led to peasants seeking alternative means of addressing their grievances, first in the form of striking and general unrest, and later in the form of armed revolution.

You do bring up the point that Communist Parties, and the PKP in particular, were committed to competing politically rather than militarily after World War II. The PKP did in fact compete politically in the form of Popular Front politics in the 1946 elections. It was only after their failure in these elections, at least partially due to widespread voter fraud and corruption, that they turned military struggle.

Also worth noting that the Manila faction was essentially wrapped up in 1950 when Lava and the rest of the Secretariat was captured. After that you have peasant leaders like Taruc running the show almost exclusively.