I am not convinced that anyone has ever used the phrase "stone-throwing devil" to refer to Palestinians, however throwing stones is unquestionably associated with Palestinian protest (Palestinian Stone-throwing), perhaps especially with the First Intifada.
It has been 30 years since the first Palestinian Intifada, or uprising, exploded onto the scene in the occupied territories.
The prevailing images of unarmed Palestinians throwing rocks at fully armed Israeli troops and military vehicles, which clearly showed the occupied and the occupier, were covered with unprecedented interest by international media.
Stories from the first Intifada: ‘They broke my bones’ (emphasis added)
Indeed, the act of throwing rocks at Israeli soldiers has become a symbolic act of defiance and resistance for the Palestinians. The juxtaposition between boys and men armed with stones against the Israeli military has drawn comparisons to biblical foes David and Goliath.
Like the kaffiyeh, the checkered Arab scarf that Palestinians sometimes use as a shield -- against tear gas, and to hide their identities -- the stone has become a symbol of their struggle.
Why Palestinians Throw Stones (emphasis added)
So, in the contemporary (American) imagination, there's already some connection between stone throwing and Palestinians.
If that connection doesn't feel obvious, also remember that the card was printed in Arabian Nights, which is set in an imaginary Arabia - so these are Arab stone-throwing devils.
Although the connection with Palestinian protestors - intentional or not - is pretty clear when you consider the above, it's not as clear what kind of statement the card would be making. That said, if there's any statement, it's probably something negative. The card is black, which is typically (though not exclusively) the color of the most evil creatures; there's the fact that they're called "devils"; there's the flavor text:
Sometimes those with the most sin cast the first stones.
None of this seems very nice to me. But as long as I'm editorializing, even if no statement were made, the mere fact that this card evokes an ongoing, often passionate political debate would be reason enough to take a very cautious stance. Why would a company that produces consumer goods want to get into that hot water?