Problem:

I read that one hard step in algae oil extraction is to rupture (or fracture) the cell walls to get the contents inside. Some people use chemical methods; some use sonication or mechanical forces.

I wonder why nobody is talking about using viruses to accomplish this task?

Viruses destroy the cells and release clones of itself. Some article states that there are plenty of unknown viruses in seawater. I'm sure a major part of it infects algae.

so any suggestions should ideally aid in this goal.