Why would this be the case?
Funny enough though the VASI appears all white (Shurg). Usually IRL, the final turn for this runway is about 41.745606°, -71.407992 (~2 miles out) with the runway @ 100’ MSL. I typically shoot for for about 500 AGL on the base to final (with power as needed). You’re right though on the full flaps being a bit early
I guess the original intention was to show the possible discrepancies between the IAS, the behavior and somehow the assist feature not reconciling (i.e. if the published approach speed is 65 kts, why is the assist claiming “I’m too fast”)
IFRs are usually to big busy airports, we do not want to be an obstacle for airliners. Some reading is here (Cessna 172/182 IFR approach speeds | Pilots of America)
I see, but it’s pretty funny that they think they aren’t an obstacle at 90kts. 
ATC usually asks you what speed you can fly and that’s it.
These 90kts are just the opinion from a few pilots, not a requirement.
In VMC you could fly clean with max cruise power.
With the weather close to the minimum I would aim to be at the target approach speed at 1000ft like most other aircraft.