It turns out the Obama administration took it more seriously than they let on:
WASHINGTON — The Obama administration was serious enough about manufacturing a high-value platinum coin to avert a congressional fight over the debt ceiling that it had its top lawyers draw up a memo laying out the legal case for such a move, The Huffington Post learned last week.
The Justice Department’s Office of Legal Counsel, which functions as a sort of law firm for the president and provides him and executive branch agencies with authoritative legal advice, formally weighed in on the platinum coin option sometime since Obama took office, according to OLC’s recent response to HuffPost’s Freedom of Information Act (FOIA) request. While the letter acknowledged the existence of memos on the platinum coin option, OLC officials determined they were “not appropriate for discretionary release.”

Having legal look at something is not the same as “seriously considering it.”
I’m a 55 year old historian who has spent his entire adult life plowing through government and corporate documents. If you have any brains at all you examine a wide range of options on every issue that comes along. Of course there is going to be a paper trail of such documents. Scrupulous historians treat them for what they are. Unscrupulous historians craft conspiracy theories around them.
None of which is to say the Obama Administration did or did not seriously consider minting the coin. All I’m pointing out is the existence of a brief legal memo proves nothing.