You are at favorable vulnerability. LHO deals and passes. Partner bids one heart, RHO opponent passes. An expert (Frank Stewart) "surely" recommends that you respond 1NT with the following: (s)J954 (h)3 (d)T (c) KQ97632. This is the case even though you have four spades. (Stewart has major issues with "Standard.") If you had (s)J954 (h)3 (d)T8 (c) KQ9763, he would "consider" bidding 1NT.
I did the same thing (bid 1NT) with a (somewhat) similar hand (neither vulnerable) and got into trouble when partner bid two spades, "reversing" with two spades, and only 13(!) points.
Under what system would Stewart's recommendation be a reasonable one? Or is it because the circumstances are (somewhat) different from mine in the above hands, where Stewart recommends running out to a "weak" 3 club bid if partner responds at the two level? Put another way, what might be the context of Stewart's remarks?