Can sodium dithionite reduce the nitro group of 2-nitrobenzoic acid?
Yes I believe it can. Dithionite is a reliable reducing agent for aromatic nitro groups. The reaction of dithionite produces an acid solution which will need to be neutralised before isolation. Anthranilic acid is not very water soluble so an extraction with e.g. chloroform should separate the product cleanly. Tetrahedron Lett. 2013, 54 (21), 2600–2603 discusses dithionite reduction of o-nitrobenzamides and refers to other papers that have used dithionite on similar substrates.