If I play Shuriken Flip from its flow cost, can it get Defied?

Yes, Defy can counter Shuriken Flip played from its Flow cost.

Defy checks the printed cost of the target spell — the actual numbers on the card, not what you paid. Shuriken Flip's printed cost is 1 Energy and 1 Power, which is within Defy's range (≤4 Energy, ≤1 Power). Playing it via Flow (3 Energy + any Power) doesn't change the printed cost, so it remains a valid target.