The entire way that Snyder dealt with LHO at the Embassy pretty well shows he knew he was dealing with an immature, idealistic 20-year-old goofball who was about to get a big dose of Soviet reality. When Oswald predictably came crawling back with his tail between his legs, it scarcely took a mind reader to recognize he had matured at least to the extent of realizing he'd made a huge mistake and wanted his mommy (well, maybe not his actual mommy, but figuratively speaking). Hence the lenient treatment upon his return as well.
Either that, or John M. Newman is right that a KGB "mole" in the CIA's mole-hunting Office of Security by the name of Bruce Leonard Solie (look him up) sent (or duped his confidant, protégé, and mole-hunting subordinate, James Angleton, into sending) Oswald to Moscow as an ostensible "dangle" in a (unbeknownst to Angleton and Oswald) planned-to-fail hunt for "Popov's U-2 Mole" (Solie) in the wrong part of the CIA.
Which, if true (as suggested by, among other things, Solie's clearing false defector Yuri Nosenko in 1968 via a bogus polygraph exam and a specious report, his helping probable "mole" Leonard V. McCoy lose Nicholas Shadrin to KGB kidnappers in Vienna in 1975, his hiding Office of Security files on Oswald from the Church Committee, and the fact that all of the non-CIA cables on Oswald's defection were arranged in advance to go to Solie's office instead of where they would normally go -- the Soviet Russia Division) means that the CIA, Snyder, and the KGB knew in advance that Oswald would be coming, but only the latter knew the true reason.
Does the above scenario suggest that the KGB encouraged and/or trained Oswald to assassinate JFK?
No, it doesn't, although Oswald's possibly realizing that he was being jerked around by both "the CIA" and the KGB might have had something to do "getting even" with both of them by killing the President.
