White has capped the left end, so this two is SLEEPING: it can never make an open four on this line, ever. Sleeping shapes are not dead — they win through rush fours, fours with a single completion point that the opponent is forced to block. Slower and less glorious, still dangerous: a rush four is a move white must spend, and spent moves are tempo. With the left end dead, only one direction still grows — extending toward the cap builds nothing, extending away keeps the line a weapon. Extend correctly.
Extend toward the open side.
Finish this step to move on.