Yes, this does get rid of the P0410 code completely.
The ECU doesn’t check the pump directly, it checks the relay and the solenoid (which you leave in place in this procedure), and it checks the O2 sensor voltage to see if it drops as occurs when the air pump is working properly (the diode provides the small voltage drop to the proper ECU pins). The basic theory (but not the completely figured out modification) is here: http://volvospeed.com/vs_forum/topic/132158-sas-delete/
People have dropped in a resistor in place of the solenoid, your idea works for that. But the solenoid is pretty small, not a huge gain there.
A great tutorial on eliminating the SAS system (secondary air system) and forever ending P0410.