... the meter on battery read 12.6 volts, held the meter on and turned key on and volts dropped down to 3.6 volts and was fluctuating a bit. Had the battery load tested at 2 shops and the battery won't pass a load test...
I HAD never heard of batteries doing this exact thing, until it happened to me TWICE in the last month. Once in my truck, and again in my car. Unlike yours, both of mine were old, 4 and 6 years old. I have had shorted batteries in the past. They were easy to spot, instead of 12 volts, they had 10, and turned over too slow to crank. I have had wore out batteries in the past, they still have 12 volts but not enough cranking amps, and again, turn over too slow to start. These last two cranked the vehicle fine until they didn't. I turned off the car in the driveway, then 15 minutes later, click click. The truck I had parked 2 hours before, then not even a click. Both charged up to 12 volts and were reported as good with my big "smart" battery charger but would not crank the vehicle. I guess my charger may not be so smart after all.
My Micro-Start PPS XP-3 got the truck cranked after having to wiggle the clamps a few times to get a good connection. It would not start the car.
... battery won't pass a load test. ... So could this have been causing the bike to blow horn and go into air ride mode due to low voltage? ...
I do not know the answer to this. I don't know the logic switching in the EHC. Maybe someone like Curtis can answer this.
... Can batteries be intermittent before finally giving out?...
Yes, without a doubt.
...Maybe the voltage would drop every once in awhile and when I use brakes etc it drops the voltage enough to kill it? Sound like a possibility or just another problem I ran into?...
It shouldn't, but it could.
With the engine running, you should get enough voltage and amps from the Voltage Regulator to keep the engine running even if you disconnect the battery (not recommended). But maybe the EHC is smart enough to know the difference, or maybe the VR pulses instead of steady output, in which case it would shut down if the battery is bad (or disconnected).