Apple has 90 days of non paid supplies on the books (and $80 billion in the bank - "cash and investments" as stated in the article).
If they'd (OK... IDEALLY) pay all of them at once and continue paying supplies as they get delivered, only then would their balance sheet look realistic.
Or, am I missing something?
By delaying payments Apple can use the cash for other short-term investment opportunities. In Apple's case, their accounts payable is probably in the billions. As an example: If Apple has a $10 billion accounts payable and instead of paying it right away they waited for 3 months and invested that $10 billion on short-term securities with a 10% return, Apple would earn $1 billion in that 3-month period vs. ZERO if they paid their liabilities right away.