You're really missing the point if you think this document is proposing an alternative to engineering. It's addressed to a subset of artists and engineers deeply concerned with the political and interpretative dimensions of engineering.
While there is usually a technical aspect to critical engineering projects, most engage issues well beyond the scope of the "sound scientific method." See: CV Dazzle by Adam Harvey. [1] I suggest looking at Garnet Hertz's Critical Making for a more informed picture of this kind of work. [2]
I read it as two things: 1) Critical Engineers are skeptical that "rich user experiences" are the most effective way of interacting with systems, 2) "rich user experiences" tend to oversimplify and misrepresent systems for the sake of usability or aesthetics.
While there is usually a technical aspect to critical engineering projects, most engage issues well beyond the scope of the "sound scientific method." See: CV Dazzle by Adam Harvey. [1] I suggest looking at Garnet Hertz's Critical Making for a more informed picture of this kind of work. [2]
[1] http://ahprojects.com/projects/cv-dazzle/
[2] https://twitter.com/criticalpdfs