Following up on the now locked thread, and without reference to the personalities that stir such emotions....

Scott MacMillan wrote:

As far as presidential knighthoods go, I believe the most recent appointment was that of President Reagan who, in 1989, was appointed to the Order of the Bath; since these appointments are "honorary" they do not fall afoul of the constitutional prohibition of elected officials accepting "awards" from foreign countries.
Actually the first President Bush was made an honorary GCB (Knight Grand Cross of the Bath) in 1993, but it wasn't to quibble about that that I was writing.

The honorary nature of the British knighthoods given to foreigners has to do with British rules, not those of the recipient countries. Being a full member of one of the British orders affords certain privileges (among them, in some cases, eligibility to be a member of the governing chapter of the order). This is not considered appropriate in the case of someone who doesn't owe fealty to the British monarch.

In addition, each class of each British order has a numerical limit; honorary members don't count against those limits.

The U.S. constitutional restriction makes no allowance for "honorary honors;" there's an "of any kind whatever" in the relevant section (Art I, sec 9). This did not apply to Presidents Reagan and Bush only because both had completed their terms before the honors were conferred. They no longer held "any office of profit or trust" under the United States, and thus didn't belong to the class of people restricted from receiving such things.