Some valid points here, but a few question marks as well.

It's suggested here that the NPA have at some point received significant aid from China, Vietnam, and the Soviet Union. I've seen and heard no evidence of that. There were a couple of abortive attempts to ship arms from China in the '70s, beyond that very little. Most external financial support has come from left groups in Europe. Cutting that support off was the main point of designating the NPA a terrorist organization (a rather awkward designation, as it really isn't one), which appears to have been pretty successful.

A bigger question mark, for me, revolves around this claim:
It needs to be understood that left-wing extremism in Philippines is not a national security issue in its current shape; rather it is a localized problem, which can be solved by local governments in coordination with Manila.
and subsequent suggestions that a "solution" would revolve around delivery of infrastructure, services, and "development" in general. This seems to me an adoption of a flawed premise that recurs often in US approaches to insurgency.

People don't go to war because the government fails to deliver infrastructure and services. They complain, but they don't fight. They fight because they see the government as a threat. The issue to me is less delivery of development than delivery of justice, and local governments aren't part of the solution, they are the core of the problem.

The NPA typically flourishes in places where local governance is dominated by powerful families controlling political dynasties. These families typically dominate all political, judicial, and economic life and operate above the law. They are abusive, exploitive, and oppressive, frequently operating their own private armies (a glorified name for gangs of armed thugs) and frequently co-opting state security forces through shared profits from illegal business.

Infrastructure and service delivery is not a bad thing, but for me the key element in reducing the influence of the NPA is a concerted effort to bring local governing elites within the rule of law. Local elites will resist, as they rely on impunity to sustain their power, but as long as these elites remain above the law the NPA will be able to cast itself as the only alternative to their dominance.

The Philippine Government is actually lucky that the leadership of the CPP/NPA and its assorted splinter factions is generally incompetent, obsessed with infighting and absorbed in their anachronistic mantras and incomprehensible rhetoric. A capable opponent could make matters much more difficult for the government. The NPA has declined as much due to its own ineptitude as to anything the government has done to fight it.

I see no need to address the NPA's claims about the US-Philippine relationship. These issues only matter to the core ideologues, who are not going to convert under any circumstances. The most effective way to reduce NPA influence is to resolve the issues that lead the fighters to fight, and those issues are overwhelmingly local. The average NPA fighter knows little and cares less about the relationship between the national elites and the US, they care about the local boss and his henchmen taking their land, exploiting their labor, and generally kicking them around.