I think Etlase is dividing "labor" into two separate types: "past labor" and "future labor."

If I am selling you a house I tell you I want $200,000 for it because it cost me $200,000 in labor to build. But you say, "forget it, I can get one built now for $100,000 in labor." The "value" and "cost" and "price" of the house now is the current or future labor, not the labor in the past that it took to make it.

So he is saying there are two labor theories of value: the "past labor theory of value" (apparently from Marx) and the "future labor theory of value" which maybe basically the same as the marginal theory of value.