We heard about and worried about the ban. But We felt no effect from it whatsoever and our bags went through security at NBO and Wilson with ziploc bags and a duty free bag. Speaking of which, duty free purchases in NBO MUST be in the sealed clear, red top duty free plastic bag to get through gate security.
The focus is to end reliance on plastic shopping bags that litter the landscape for a couple miles as you approach any village. So the focus will be on retailers at first.
As a tourist I wouldn't sweat it. But I also wouldn't flaunt it.