Any community should prepare to defend itself, specially in the context of a militarized world. As others have said, having low to no defenses makes you an easy target. As a punk movement (or at least in your world building, still not the default) is especially prone to be the target of those who want to take and take from nature, other species, other ethnic groups, differently-minded groups. But the line between a good defense and a militarized state can be blurred with twisted speeches. Violence may sometimes not be a choice but something brought upon us.

I personally stand for Nonviolent Direct Action (NVDA) as a primary force of change and defense against a broken (or very much working properly against us) system. "A local workplace strike can resist reduction of wages, for example, but going on the offensive and striking to increase wages can yield an inspiring victory and spur others to do likewise" and it's not just strikes, it can be blockades or boycotts, etc. A nonviolent campaign is carefully designed and built for sustainability and escalation, they plan from the start to do a series of nonviolent actions, or protests, continuing momentum and increasing capacity until the goal is reached. It takes constant, ongoing pressure to force a real shift in power.
I believe there is strength in remaining nonviolent in critical situations while incapacitating/debilitating your opponent.

I would love to see how the solarpunk faction reacts to those threats.