Catalysis of the reaction: dTDP-4-dehydro-2,6-dideoxy-alpha-D-allose + NAD(P) = dTDP-(2R,6S)-6-hydroxy-2-methyl-3-oxo-3,6-dihydro-2H-pyran-4-olate + 2 H+ + NAD(P)H.
dTDP-(2R,6S)-6-hydroxy-2-methyl-3-oxo-3,6-dihydro-2H-pyran-4-olate 3-ketoreductase (dTDP-4-dehydro-2,6-dideoxy-alpha-D-allose-forming) activity