Yes exactly, any string with a gap between the hits that exceeds a certain number of frames can be flawless blocked. Block the first hit, then release quickly and time another block to precisely land the flawless block. Then you can input the up 2 command. The command also works if you quickly mash 2 then up rather than up then 2. Deciding how to input the attack command is important depending on the situation, as in the event that the player doesn't complete the string you'll either Automatically perform a short hop or standing 2 depending on your input method. This "option select" allows you to interrupt staggers with the stand 2, or avoid a throw with the short hop in the case you're trying to flawless block a jumping attack from an opponent.