That assumption, in direct contradiction with safety requirement, is now proved wrong. Two times, with a lot of peoples killed.
You have not provided the authority's safety requirement on a factual basis, so it should be noted to all here that your opinion is simply speculative. Considering the information you provide in this thread, such speculation should be considered unreliable.
I have in my post #2965 2 weeks ago
AC 25-7D document https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25-7D.pdf
10.2 High Speed Characteristics—§ 25.253.
10.2.1.1 The maximum flight demonstrated dive speed, V DF /M DF , selected by the
applicant, is used along with V D /M D when establishing V MO /M MO
accordance with the associated speed margins
under the provisions of
§ 25.1505. Both V MO /M MO and V DF /M DF are then evaluated during flight
tests for showing compliance with § 25.253.
10.2.1.4 The airplane’s handling characteristics in the high speed range should be
investigated in terms of anticipated action on the part of the flightcrew
during normal and emergency conditions.
10.2.1.5 At least the following factors should be considered in determining the
necessary flight tests:
10.2.1.5.1 Effectiveness of longitudinal control
at V MO /M MO and up to V DF /M DF
10.2.1.6 Section 25.1505 states that the speed margin between V MO /M MO , and
V D /M D or V DF /M DF
, as applicable, “may not be less than that determined
under § 25.335(b) or found necessary during the flight tests conducted
under § 25.253.” Note that one speed margin must be established that
complies with both § 25.335(b) and § 25.253. Therefore, if the applicant
chooses a V DF /M DF that is less than V D /M D , then V MO /M MO must be
reduced by the same amount
(i.e., compared to what it could be if
V DF /M DF were equal to V D /M D ) in order to provide the required speed
margin to V DF /M DF
. In determining the speed margin between V MO /M MO
and V DF /M DF
during type certification programs, the factors outlined in
paragraph 10.2.1.5 above should also be considered in addition to the
items listed below: