Clean or change out the spark plugs after seafoaming, you'll know why when you pull them.

It isn't seafoam that damages the O2 sensors, it's all of the crap in the intake manifold and combustion chamber floating down the exhaust that clogs them up.

I've read that many people just simply remove the O2 sensors, clean it out with either electrical cleaner or carb cleaner, and throw it back in with no problems. I, personally, saved my old O2 sensors just for this cause