SAG supported the WGA during this strike, so the reverse is expected, as long as the SAG demands are reasonable. No one will "like it". The studios can do their part and negotiate in good faith.
Unfortunately, the writers won't really be affected by a SAG strike as they can easily keep working on scripts (and being paid) while SAG is out. They would actually be the only group that could keep working with a SAG strike as their job does not depend on anyone or anything except their own pens/paper/computers (assuming studios are still buying scripts during the SAG action).
I'm hardly an industry insider, but I don't think what you said is completely true. Certainly writers can write ahead of actors acting, but they do need orders for their work to get paid. How many episodes ahead would be ordered if there were no actors to act? I'd say there is some insulation, but it isn't total. Hopefully all this is much ado about nothing and the SAG won't have to go through a strike.
I notice that he neglects to mention that he'd be doing as much guild writing on the picket lines as he would off. Of course all of the older writers who live off residuals now want the guild to hold out for the best possible deal. They don't have anything to lose from the strike.