“No more will the NCR continue its aggressive campaign of Eastern expansion. You can put a single point into any of your S.P.E.C.I.A.L. attributes. You also gain reputation with Caesar's Legion for annihilating the NCR's homeland, but lose reputation with the NCR.”— In-game description
PC The SPECIAL point must be added. If you have them maxed out, then you will not be able to continue. [verified]
FIX: PC users can use the console command "cam" that will just close the menu and you'll be able to continue.
FIX: If you have the DLC Old World Blues, you can transportalpond back to the Big MT and then back with getting the perks. Can only be done if missile has been fired at someone, however, The Long 15 will not be accessible.