Dear God, see what happens when you mothball your battleships? Next thing you know, every tin-penny wog monarch on the planet feels free to imprison Americans for not kissing royal arse.
Is this what we shot all those damned redcoats for? So some foreign king can charge an American citizen with lèse majesté?
Teddy Roosevelt would have landed marines already. That fascist Wilson would have sent Black Jack Pershing at the head of a column of cavalry. (Er, metaphorically, at least, since Thailand's rather a swim, even for a cavalry horse.) Heck, even that yuppie farmer Tommy J would have had the U.S.S. Constitution delivering broadsides in the mouth of the Chao Praya by now.
Laying hands on a sovereign citizen is every bit the act of lèse majesté that calling Rama IX a great big poopy-head is. Americans don't bow to kings. (Ahem! Barry! Stand up straight, dammit!)