After reading enough of your posts, I recognize that you are pretty thorough. I'll mention a few things I know to see if they can help. I worked on radio's when I was an Electronics Technician in the Navy.
Does the fuse only blow if the antenna is connected?
Even if the antenna had a dead short, this will not normally fry the fuse with the radio in receive mode.
At this point, I'd open up the radio, and see if possibly something has come loose, or worn through to the case that can be causing the short.
I'd say also try disconnecting the Mic and Antenna, and turn the radio on and see if the fuse blows. If not, switch the radio off, and connect the antenna again. Turn it on. If the fuse doesn't blow [and from your description of the resistance readings I don't think this is a problem with the Road Pro at this point] then it is something with the microphone. Maybe the radio is in both transmit and receive mode due to a short, or perhaps a loose wire in the Mic plug shorting to ground.
Right now, I almost suspect something with the Mic more than the antenna.
Again, even if the SWR is far off, unless the Mic is keyed, the fuses should not fry.