I don't disagree with anything that you say.
However, I will be replacing the old dipstick with one that is not made of metal with square edges, does not over-read by virtue of being calibrated for a tank containing 1.5 US gallon more capacity, and which is slightly shorter so that when the cross-bar meets the top of the filler neck the base of the dipstick is not in contact with the floor of the tank.
I don't see the disadvantage in designing out the residual risks (even if very small) but more so when multiple pilots use the machine on a lease-basis (if the tank lining were to be damaged I would be unlikely to be able to pin the cost on the person who damaged it), and the machine is used for training purposes so PUT will also be 'dipping'.
Each to their own
John