There seems to be a subtle irony at work here [courtesy of RNG]
First, see the Artscroll Siddur Friday Night Maariv p.336 in the footnotes to V'shamru.
The first paragraph there prohibits interrupting between Haporeis and the Amidah. It then gives a heter for adding V'Shamru despite that prohibition.
Second, see the very next paragraph. There Artscroll denounces making exceptions re: Sabbath Observance for the sake of constructing the Tabernacle. In this second paragraph, the concept of making exceptions to Halachah for some "higher purpose" is now being opposed!
Does anyone notice the irony of these 2 statements juxtaposed together?