Honest question. Why did they not put the company into a TH before market open?
Because the market wasn't open and they already had the announcement. Trading Halts are usually for pending announcements not yet finalised.
Also, if eventually there are no buyers at .001, does the company have no choice other than VA/ liquidation/sell of parts?
No share price and market depth alone does not dictate liquidation. The issue only comes to a head when they run out of money and need to raise more from the market. Liquidation is a high possibility from here though depending on the claim by Mylan of legal costs.