Why can't the Droid 2 connect to 5 GHz WiFi networks?
The WL1271 WiFi chip in the Droid 2 does not support 5.0 GHz networks, so there's sadly no possibility of a workaround.  Its "better cousin", the WL1273 chip, does support 5 GHz networks; unfortunately, Motorola went the cheap route.  You can get more info on these chips at the Texas Instruments website.