Seems like Fred Hoyle, in the 1980s, also thought that earth's water could have been locked up in minerals in the early earth. There is no escaping the fact that indigenous water could not have survived early earth formation processes as a vapour or a liquid. The interior of the earth, probably holding many ocean equivalents of water locked up in mineral form may have outgassed a large or only a small portion of its present ocean (on the surface), and some fraction may have come from comets. The latter is an add-on to provide a nod to mainstream views at the time that water on earth arrived via comets. Seems like there is nothing new. It's all been thought of before – by someone. Take the end of Ice Age comet idea (the Younger Dryas Boundary Event) – C Warren Hunt was saying something similar 30 years ago (with a slightly different date).