It is, and thanks for pointing that out, but briefly - here's the wording from CS.23.677 (pretty much the same wording is in FAR23)...
(d) It must be demonstrated that the aeroplane
is safely controllable and that the pilot can perform
all the manoeuvres and operations necessary to
effect a safe landing following any probable
powered trim system runaway that reasonably
might be expected in service, allowing for
appropriate time delay after pilot recognition of
the trim system runaway. The demonstration must
be conducted at the critical aeroplane weights and
centre of gravity positions.
Checking, an interesting point is that not only is this wording not in VLA or Section S (nor 22 or the old Section K), it's not in part 25 either.
Even here, there's nothing about immediate behaviour in the event of a runaway - of course a good certification team will look into this anyhow, but it's a bit of a hole, and in regards of sudden manual deflection of a mechanical system, as in the case of the EV97 fatal, there seems no guidance anywhere, for any class of aeroplane.
G