Let him do the resealing. Give your rubber roof material mfg a 1-800 and ask them what they recommend.
My 31' 1997 5er with a rubber roof has never had any type of coating. It no longer white after 22 years however this unit has sat in its trailer barn when not on the road.
I do a roof inspection (everything) twice a year (spring and late fall) and reseal spots here and there with Dicor if needed maybe every 5-6 years. Some OEM seal areas is still doing its job. The trailer was nine years old before the sealant around the skylite and one roof jack needed a bit of self leveling Dicor.