If I am understanding you seems your asking if the stairs violate this:
110.26(C)(2)(a) Unobstructed Egress. Where the location permits a
continuous and unobstructed way of egress travel, a single
entrance to the working space shall be permitted.
I saw no specific reference to stairs for or against and think that stairs do not obstruct your means of egress, of course this is 600V nom or less. IMHO I think you good and may not even need the second means of egress but more ways out the better, but more exspensive.