This reminds me of arguments that money must be on the gold standard to have value. Any theory that doesn't explain observed reality is not a theory, and it is definitely observed reality that the concept of value has no strict ties to work.
So if it is not (only) the amount of work that makes up the value of goods or services, what (else) is it? And I am neither interested in the supply and demand situation which may cause the price to deviate from the value, nor in the use value.
The labor theory of value is a mistake with roots in both Adam Smith and Karl Marx. The Austrian school of economics explained and demonstrated how it is utterly wrong, and they have presented a much better theory. Look up (and read) Carl Menger.
George Reisman has developed a brilliant, modern presentation that dismantles the problems with the labor theory of value, and the related exploitation theories. [1]
I read the essay but only once so far, so I may have missed some things. It doesn't seem to point out any flaw in the theory but rather try to present an alternative. But this alternative I find utterly unconvincing because it is full of errors and holes. I would really like to provide critique to all those points but that would become a piece longer than the essay. If you like I will elaborate on specific points.