We may need clearer pictures to see if those special barges would be equipped with CIWS or not. Having extra CIWS and short-range low-altitude air defence radar could mitigate such exposures and threats posed by anti-shop missiles.
You don't even necessarily need the barges themselves to have it -- the nature of the distances involved means low draft escort ships with their own SAMs and CIWS could do the job.
I could even see them building relatively light displacement, low draft "escort barges" that are only a few hundred tons but are installed with SR SAMs or gun based CIWS to act as closer in last ditch defenses.
This is ignoring of course how such an operation would have substantial air and naval escort and overwatch in general, not to mention it would be preceded overall by a large scale bombardment of the immediate beach, and having secured air and sea control with requisite interdiction of identified adversary artillery and fires groups and C4I, to overall reduce the ability of an adversary to resist a landing with either maneuver forces or residual artillery forces.