I give my two greenies without a problem.
They love them. Frankie used to have a "gulping" problem = swallowing things whole or eating very fast.
Since he has quit I give them to him too.
I always supervise my two with ANY treat they get.
If your dog likes them and doesn't swallow them whole or in big chucks then I wouldn't have issues with it.
You have to understand that Greenies are very popular and with that a very small percentage of dogs may have adverse reaction, as with anything.