Since it looks like EM doesn't calculate that measure, you could do the following in a SAS Code node after the Model Comparison node (not sure if this is the best way, but I think it should work):
 
data mae;
   set &em_import_data end=last; /* you can use another partition here: &em_import_validate or &em_import_test */
   retain sae nobs 0;
   sae + abs(R_target); /* R_target is the residual.  Put the name of your target in for target */
   nobs + 1;
   if last then do;
      mae = sae / nobs;
      output;
   end;
run;
 
proc print data=mae; 
run;