If you equip the Hulkbuster Left Arm to Doctor Octopus can he use exploit weakness with his free action flurry? Or, since, both require a close combat action, you can use either flurry or exploit weakness, but not both together?

FLURRY
Give this character a close combat action. After the close combat attack resolves, it may make a second close combat attack as a free action. The first attack doesn’t activate the Damage Depletion Modifier.

EXPLOIT WEAKNESS
Give this character a close combat action. Damage from the attack is penetrating damage.

They both require a Close Combat Action to activate, therefore you would not be able to use them together.

Just to be clear, he can't choose to use Exploit Weakness instead of Flurry with his trait. It specifically lets you use Flurry as a free action, nothing else.

thanks for the clarification