This is probably why. Whelan is a total dips**t who got kicked out of the Marine Corp for trying to steal $10k in Iraq.
Whelan was either the stupidest guy on the planet who contracted to do the stupidest swap of information in the worst possible city in the world, or he was set up by the Russians in order to be used later in a swap like this (but then Griner came along and is a better 1 for 1 swap). For me, the latter scenario is slightly more likely than the first, but I've seen stupider things.
Also, Whelan's family was told yesterday that he wasn't coming out because there was no way the Russians were agreeing to a 2 for 1 swap on this and his family was supportive of the swap (but that's clearly under duress, if they made a stink, Biden/State would stop trying to get him out altogether). This is a MUCH bigger, and more important, political win for Putin than Biden at a time when Putin desperately needs a win at home (way more than this gives Biden here).
People REALLY need to stop with the "Whelan Marine" thing... they look really, really stupid. I think most Marines would choke Whelan, with his own hand.