He is certainly targeted and watched. If you send him money, you will likely be watched more carefully as well. Buying his book is a symbol of defiance more than anything else.
That said, Snowden is not covered by official sanctions and does not even come up on Dow Jones as PEP or person of interest.
source:
sanctionssearch.ofac.treas.gov
dowjones.com
Edit: brackets
edit2: also, the fact that he may be potentially indicted does not mean it is illegal to give him money. Those are two separate issues
You right in a sense that when you read this, Snowden could easily be argued to fit the mold.
However, you will note that it later says that the actual designation ( verified here with treasury link I added ) is up to SOS and other involved individuals.
Note, that at the time I checked it, Snowden was not on that list and apparently has not been since issuance of this EO.
At least not yet.
edit, because there always exceptions: see wikileaks and note neither he nor his creation was sanctioned by OFAC either. However, that did not stop the state from making donations.. challenging.
2. Is Bitcoin money?