I haven’t read the book, so I hardly can tell what the author actually means. However, reading religious texts as if they are science texts, or taking them literally, is usually a mistake. They tend to be parable, metaphorical, etc. You’re to consider how it lands, but for the real religious texts, this means a lifetime of contemplation, not a “here’s the formula, now apply it literally”.
But as an example out of context how I relate to / translate these is:
“If the soul is very clear that staying does not serve its higher agenda (...) the soul is going to leave, and nothing will stop it—nor should anything try to.”
It seems to me that the soul “staying” could mean either death, or more likely and more commonly, the soul fading into subconsciousness as ego concerns take over the consciousness, which is what happens to most teens and adults. Tell your genius child they will never be able to be a dancer or artist in the world, and that genius in them fades away and hides and is forgotten by the ego which wants to survive, and they go on to be an empty unfulfilled banker and die of cancer or heart disease 30 years later.
“The spirit will never, ever, force its desire on the present, conscious, physical part of you.”
The spirit is not the same thing as your conscious or your physical body. I’m not sure exactly what the author is getting at here, but I don’t see it as a contradiction to the first statement. I suppose if you read the first sentence as saying the soul can get so bummed out that it kills the body, then you might take that as “forc[ing] its desire” on the body, but I don’t think so. The body and soul and consciousness all coexist. If one of them gets sick and dies, I wouldn’t call that “forcing its desire”, but rather it dying off and possibly (or not) taking the others with it, not because it wants to, but because it’s dying. But it seems to me what generally happens is when the spirit has a desire, and the conscious and physical parts of you have other agendas, you just get some input in the form on ennui or sadness or lack of enthusiasm or something, but it doesn’t force you to stop doing your dumb homework, or not eat. And what usually happens when the soul refuses to stick around for the situation, is the soul, or really parts of it, stick around but hide out. There’s a whole ancient trans-cultural shamanic practice generally called “soul retrieval” which aims to rouse and welcome back those parts.