In seven operators, I've never seen anyone use it as a crosscheck, Herod. Rad alt and baro alt seldom match, really just over the sea and Norfolk, so (probably) nobody has an SOP to do that.
We do, although unless you’re over the sea or flat ground there’s not enough information on the chart to tell much more than yes, there’s something underneath you.
Back to the incident, I too am perplexed as to how they ended up as low as they did if they were in constant visual contact with the runway & slope guidance. Must have been four reds for a while but corrective action only taken when within seconds of flare height over the ocean.