The problem with that is how do you measure viscosity of the resin in a laminate?
it is quite plausible that those figures are accurate from mechanical testing and enough research but they are not really that helpful in that format.
It makes sense that as a resin system begins to cure, the viscosity will rise, and in practice a point will be reached that vacuum bagging would have minimal or no impact on consolidation because the resin has thickened up too much. So the statement and theory is fine.
In practice, with no viscosity measurement, most people are likely to ignore the first part. In practice, by the time you have laid up the part and then got the vacuum bag on it, it is likely to be fine for pulling vac on. I have not heard of people having issues from vac bagging too soon (not to say it cant happen.).
In terms of the second statement, in practice most people tend to aim to work quick enough so the resin has no where near gelled by the time the bag pulls down so again it is unlikely to be an issue for most users.
In my experience, the most common factor for dry spots is either poor application and consolidation of the first layers of resin and fabric and/or excessive vacuum used during the bagging stage. Generally these are problems found with inexperienced users and with experience, people tend to improve their laminating technique and find a vacuum level sweet spot that works for them.