That's what he's saying. There are seals in there, under the head you loosen and tighten, that can leak. Usually they will not leak due to simply being opened and closed. They'll leak because whomever is brazing right there puts too much heat for far more than the neccessary length of time and melt the seals.
No other way to pressure test a condenser. Also, remove the shraeder valve cores before brazing as well.
I'm assuming this condenser has no refrigerant in it so removal of the cores will not deem the service valves need be closed. The valve cores will have to be back in before the pressure test as the service valves will need to be open.