as I recall the questions was asked at an ASPPA Conference many moons ago, so many in fact, that...
well, as I recall, the issue was discussed from the podium. and the original question was at 6% not 10%.
the answer was basically as described above, but perhaps in more cautious terms.
I believe the IRS suggested, as noted in the original post, this may be 'unreasonable' possibly subject to a BRF test - while yes currently available to everyone, effectively it was not.
given the fact you are giving a free ride on ADP testing and if only HCES are able to take advantage of it, the IRS might have problems upon examination.
suppose NHCEs were smart enough (ha ha ha), I said suppose to write the IRS and ask
How come the HCEs can defer out the wazoo and get a match and we get nothing because we can't afford to defer but limited amounts
would such a plan ever get caught?
or maybe, perhaps put another way, if someone asked me to implement such a plan I would have them seek someone else to run the plan.