If partner opened AJTxxx x xx Axxx in 2S, I would not make
an issue of it, but I think the telling points for me are that the
hand's 2 QT are also 4 controls, the hand has only 3 fast
losers, and the hand is clearly an opening bid per KSU C
where EK's example differs by the minor suit for Axxx and,
admittedly more significantly, the singleton in a minor rather
than hearts.
KQx xxx xxx KQxx evaluates to 9 support after demoting for
the flat hand. However, it features 2 honors fitting partner's
suit and concentration of honors in 2 suits. I think I would
stretch it to a limit raise via 1NT:
1S 1NT
2S 3S
which gives opener the message that responder has neither
4 spades nor a singleton. I personally think opener has
enough to gamble 4S.
Digressing some and using Petkov Zar's evaluation, where
game at MP~51 Zars, Zars = HCP + Controls + ((a+b)+(a-d))
where a, b, c, d are the hand's suit lengths in descender order:
Opener's AJTxxx x xx Axxx evaluates to
9 HCP + 4 Controls + (6+4)+(6-1) = 28 Zars,
about a queen above a 26 Zar minimum.
Responder's KQx xxx xxx KQxx evaluates to
10 HCP + 2 Controls + (4+3)+(4-3) = 20 Zars,
Responder adds a fit Zar for each of the SK, & SQ,
making 22 Zars, which is a minimum-ish limit raise and
made via 1NT with 3 trump and no singleton.
After the limit raise, opener adds 3 superfit Zars making
31 Zars, close to an ace above minimum and a clear
reraise to 4S.