If I activate the [Activate: Main] effect of my "ST10-001 Trafalgar Law" and the number of DON!! Cards on my field is at least 2 less than the number on my opponent's field, can I use that [Activate: Main] effect to play this "OP07-064 Sanji" from my hand?

[OP07-064_p4] - Sanji (One Piece Promotion Cards: Championship 2024 Top Player Pack Vol. 2) - One Piece Card Game

[OP07-064_p4] - Sanji (One Piece Promotion Cards: Championship 2024 Top Player Pack Vol. 2)

Card Description

If the number of DON!! cards on your field is at least 2 less than the number on your opponent's field, give this card in your hand -3 cost. [Blocker] (After your opponent declares an attack, you may rest this card to make it the new target of the attack.)