Those are Hilton Head - not Barony - lifeguards. Hilton Head offers umbrellas and beach chairs for rent in numerous places along the beach. It's a benefit that many of us take advantage of on every visit.
As the tide goes out (it's close to high tide now - I'm down the island at Grande Ocean), you'll see that there is tons of space for your own set-up if you prefer.
Do the lifeguards spend a significant amount of time with rentals? Yes, they do. Thus, are they lifeguards who double as rental agents or are they rental agents who double as lifeguards. Either way, the city has decided that's how they want to staff the function. With only one lifeguard per station, you'll likely see no lifeguard there during lunch and other breaks, especially starting Tuesday, unless there happens to be a relief lifeguard available. Again, that's how the city - many years ago - decided to staff the function.
I don't recall ever reading of complaints about the program - either here or in the Island Packet.
Incidentally, can you plan on joining a group of TUGgers tomorrow morning at 10 at Cafe Europa in Harbour Town in Sea Pines? There's a thread about it on the Eastern forum.