Those familiar with the story of the Red Sea crossing will remember that the whole point of this remarkable deliverance was that the Israelites did not get wet at all. It was the Egyptians who were immersed. Nevertheless, although the Israelites remained dry, they were still baptized into Moses.
Wilson is discussing 1 Cor 10:2.
The one problem here is that the Scriptures say the Israelites did in fact get wet (Ps 77:17), though it was a baptism by sprinkling/pouring (literal rain, but "the clouds poured" poetically) rather than the very immersive baptism that met the Egyptians. The (Glory?) cloud rained on them as they crossed.
