Is Sous Vide Oil Infusion with fresh herbs or garlic a practical technique to avoid botulism risk?
Pasteurization will not do anything to reduce botulism risk. Botulinum spores are very hardy, requiring high temperatures (250f) to destroy them. If you use the method you describe, any spores that may exist will still be there, and a nonacidified, oxygen-free environment would be ideal for them to become active. So my recommendation would be to not take this approach.