I think the refunds on tickets for flights from now to 31 July have been driven by the ACCC threat of massive fines - up to $1M per instance, i.e. per ticket sold - if they continued to take money with no reasonable expectation of being able to fly the pax.
The refunds have not been driven by some long term strategic plan. Tiger are likely living from day to day in a reactive mode right now while they attempt to weather out this storm.