This isn't dangerous just because of airframe stress. Think about the aerodynamic implications of side-slipping a SWEPTWING aircraft. The downwind wing's "sweep angle" is rapidly increased causing airflow over the wing to slow thus decreasing lift substantially. The oposite is happening on the upwind wing. (Think of it as a sort of Dutch-Roll.) Not only can the downwind wing ubruptly stall but the upwind wing can quickly rise due to the increase in life on that side. This is how a spin happens. All of this is exagerated by flap deployment.
The above senario could be terrible not to mention the effects of the sideslip on the engines (possible airflow reductions, over-temps, compressor stalls).
Bottom-line, sidesliping a large, swept-wing, turbine powered airplane close to the ground could go bad very fast.