What photos? Can you post a link? I can't seem to find a 14" version of the MS on CZ's LE site or in their civilian catalog, just 11" and 9" versions.
Might you be confusing the 11" version for the 14"? My 14" Bren 2S in 5.56 definitely does have a bayo lug. Both the 7.62x39 and 5.56 versions of the 14" Bren 2S have the lugs.
By the look of pictures on gunbroker, the 14" 5.56 Bren 2MS has the lug, only the 7.62x39 version doesn't. Thus my curiosity.