No. High oxytocin is present whether you orgasm or not, as we just established. I expect this to help productivity. I also expect that orgasm would

• Hurt productivity, because "so sleepy and satisfied, why do anything?" (from low dopamine, possibly from high prolactin)
• Help productivity, because "feeling so relaxed, doing things that normally make me so anxious and icky is so easy right now" (from high prolactin; sex without orgasm (high-oxytocin, low-prolactin) does provide some pleasant feelings but not this specific effect)
• Help productivity overall, relative to sex without orgasm