Exactly. Deflagrate is triggered by normal attacks, but when you make a Tempest Attack you're not making normal attacks, as it's specifically called out as not being a normal attack. It's the very first sentence under Tempest Attack. "Rather than attacking normally..." There's a reason that rule is worded in that way, while Deflagrate includes the wording "After normal attacks...". Both abilities aren't intended to be used together. The only way to activate Deflagrate is to make your 4 regular Attacks at Initiative 4.