Double hmmm. I don't think Walker proposed to use both of their engines. As for the condition of their equipment, I seem to remember reading that this eastern line was in very poor shape. Perhaps their problem was the road itself versus the rolling stock? I wonder if someone intervened on behalf of the RR on the grounds that they needed both locomotives to provide service for military shipping. I do know that at one point Magruder suspended civilian passengers on that line.
Magruder used the Texas railroads, based on Houston, as the essential backbone of his defense plan for the coast. I find it very hard to believe he would use one of his essential locomotives, that could service the whole central and eastern coast, for the construction of one TB that might be able to defend one spot on the coast. I just do not see him making that trade-off.