The moral case for destroying fossil fuel infrastructure
If someone has planted a time bomb in your home, you are entitled to dismantle it. More to the point, if someone has placed an incendiary device inside the high-rise building where you live, and if the foundations are already on fire and people are dying in the cellars, then many would believe that you have an obligation to put the device out of action.
This is the moral case which, I would argue, justifies destroying fossil fuel property.
If you need morals to lash out against something actively hurting you so be it. Rock on to anyone destroying any infrastructure.