The brake shoes need the support that the lip makes to restrict them from move sideways and touch the back of the drum, that is the danger. If it is safe to let the damage be depends if the the damage is at risk be too little support for the shoe, or snag it, or if there is a crack further in the thin lip that may risk break off later.
The top can be ground off and a washer welded on the stud. The stud can be shortened a fraction and the shoe pivot area can be trimmed down if the welded on washer is thicker than the original lip. The important part is to check so the repair does not touch the back of the drum at any circumstances.
