They would not be the only group to think of this, in Canada we have suspected that the big Fort Mac fire in the spring a few years back had an arsonist origin, it was much earlier than the usual timing and certainly no possibility of lightning. Other groups who might conceivably start fires include Islamist terrorists, Chinese saboteurs, anarchists broadly speaking (beyond Antifa) and people looking for work as forest fire crew members. That last one has certainly happened in the recent past on more than one occasion.
Then if we add jerkoffs who toss butts out of their moving vehicles in tinder dry forests, vehicles parked on dry grass and the operators don’t notice they started a fire, etc, it’s a wonder the whole country hasn’t burned down.
This cold front is still coming for Phoenix area, a wave developed around Prescott holding up the timing by 1-2 hours, expect it to get very windy by afternoon rush hour with scattered thunderstorms there, a line of them extends through east central AZ with a few pop up tops showing now in the north Gila valley. It could get quite dusty between cells.
I can see tremendous amounts of smoke on visible satellite imagery heading south-southwest from fires east of Redding, spreading out over the northern Central Valley. So far it hasn’t gotten too windy in the valley, some reports of NNW 30-40 mph around Sacramento. Other areas have remained fairly calm, thinking the outflow will begin soon and as with the Paradise situation the strong winds might hit this evening and into the overnight. Be prepared especially if you have active fires to your east through north.