Sure
onesCount // Select[Length@#[[2]] > 0 && #[[2, 2]] == rows - 1 &] // Map[First]
(* {1, 2, 62, 82, 96} *)
With some helper functions
countsOf[n_, matrix_] :=
Table[{i, Flatten@Tally[Select[matrix[[All, i]], # == n &]]}, {i, 1, Last@Dimensions@matrix}]
withCount[n_] :=
Select[Length@#[[2]] > 0 && #[[2, 2]] == n &] /* Map[First]
Index of columns in colmat
that have 10 2's
countsOf[2, colmat] // withCount[10]
(* {97, 100, 110, 129, 139, 143, 149, 150, 153, 174, 205} *)