So much nonsense packed into so few words:
"But the lefty Sraffian model has only labour and time as inputs." -- Nick Rowe
I do not know what politics has to do with it. I'd like to see some evidence of the political beliefs of, say, Neri Salvadori. When Sraffa states, in the preface of Production of Commodities By Means of Commodities, that "Others have ... independently taken up [similar] points of view," I think he includes John Von Neumann. Von Neumann wanted to wage an atomic war against the Soviet Union. I guess Rowe must think Von Neumann was a Trotskyite.
The Sraffa model, of course, includes non-produced inputs other than labor. "Land" is the title of Chapter 11 of Sraffa's book. I have attempted to explain some of the points in this chapter here and here. Heinz Kurz, Neri Salvadori, and Bertram Schefold are just some of the economists who have contributed to the literature building on Sraffa's analysis of land.
To address another Rowe misconception, Sraffians have also analyzed heterogeneous labor. In fact, "Heterogeneous Labor" is the title of Chapter 7 of Ian Steedman's book, Marx After Sraffa. I have an example with heterogeneous labor here.
The bit about time being an input in Sraffa's model is apparently some convex combination of a lie and begging the question. Sraffa explicitly states, in the title of his book, that he is considering production processes with inputs of commodities. These commodities include seed corn, iron, pigs, and so on. Although Sraffa assumes a yearly cycle of production for convenience, time is explicitly not an input in Sraffa's model. In fact, Sraffa can be said to have proven that "capital" cannot be reduced to time. In the case of joint production without land, the technique cannot even be reduced to labor inputs applied over time. (By the way, in the first chapter in her Essays in the Theory of Economic Growth, Joan Robinson explicitly analyzes an economy in which robots are produced by robots.)
Does anybody expect Rowe to acknowledge that he has no concern whatsoever over whether what he says is true or even makes sense?