Do you always have to remove moldy drywall?

Whenever I see moldy drywall, I recommend physical removal. But, every now and then I come across a project where physical removal is not physically or economically possible. The most recent case was a large (22000 SF) home under construction. The drywall was installed over metal framing prior to the roofing system being complete... and the rains came. This particular home is unique in that there is literally hundereds of miles of electrical wires, T1 lines, cable, phone, plumbing, conduit, ductwork, etc, and all of it goes through the drywall in the ceiling cavity. If you have ever seen metal framing, you know that the drywall is installed on a wall, and then perpendicular walls are installed (this is for fire rating). The end result is that drywall is sandwiched between metal studs and framing members. Add this fact to the fact that all the wires and conduit penetrate the drywall and you realize that removal and replacement of the drywall in the ceiling cavity of a 22000 SF mansion cost more than most people pay for their entire house. In the IICRC S-520, Section 10.10 Deviation from Removal Process, it states "...mold must be controlled at its source, physically removed during remediation and that attempts to kill or encapsulate mold are generally inadequate remediation measures. At the same time, there is recognition that unique circumstances may be considered under specific conditions. This may result in a decision to deviate from portions of this Standard and it is highly recommended that these situations be identified and evaluated on a case-by-case basis". What the IICRC is saying, in essence, is that the Environmental Consultant can use his/her professional judgement to determine if this situation exisit, and then make altermative recommendations such as treating and encapsulating.