The US space industry isn't that big. The same people are all over the place and many have been in the industry for many, many decades and had many positions. And many of the people interested in Mars are also interested in space in general and in military space in general, this isn't surprising.
When SpaceX got started, clearly with the focus on Mars he tried to pick up well known experts. Griffin among them, again this isn't surprising. And when SpaceX did that it was not at all clear that Griffin would be able to be NASA Administrator. And because Griffin as a very opinionated person he didn't get along super well with Musk and instead went to In-Q-Tel. But he knew that SpaceX was serious and Musk had the financed to put more money into SpaceX then most other companies.
Also you will see the Griffin was also at Orbital Sciences as CEO. So he had some links to both competitors in the COTS competition and likely knew or worked with many others over his career.
And if you do the research on COTS instead of just saying 'directed the first few $billion to a zero-experience SpaceX' is just a major oversimplification. COTS started by other people inside NASA who were sick of the old practices.
The first round of COTS were selected May 2006. SpaceX launched the first Falcon 1 in March 24, 2006. So during COTS SpaceX was not some 'nobody' company, NASA was aware of them and while today 'private company close to launching Orbital rocket' isn't impressive anymore, back then it was very much so. SpaceX had done more already then many other companies in the competition.
Also, if you know anything about NASA processes, the Administrator can not just 'pick' whoever he wants. There is process that is guided by lots of requirements and so on. Unless you have any actual evidence that this process was somehow corrupt and that Griffin conspired to give money to SpaceX above everybody, then you better show some evidence for that. And 'worked for few month with Musk' isn't evidence. And in fact SpaceX was selected because many of the NASA people who did the selection were impressed with SpaceX as many have talked about in interviews over the years.
Given that SpaceX was selected and was successful, its hard to argue that NASA made the wrong choice. NASA selected 3, SpaceX, Kistler and Orbital, and 2 of those were successful. So it seems the program wasn't run by idiots.
Literally the whole 'evidence' for 'theory' is Mike Griffin likes missile defense and he has been in the Space industry for many, many decades and knows everybody. That's it, that's your evidence. Griffin and others like him never made secret of what they wanted. That doesn't mean that when he worked at NASA missile defense was the only thing he ever thought about and that all his actions at NASA were only with the singular goal of missile defense.
If you want to make the argument that orbital missile defense is a bad idea, that's fine, you don't need need to make up a bunch of conspiracy theory where non exists. You just make yourself look silly.