Once again. Wrong. Especially in a population where people are vaccinated against the disease.
From the American Medical Association:
Historically, the rapidity of smallpox transmission throughout the population was generally slower than for such diseases as measles or chickenpox. Patients spread smallpox primarily to household members and friends; large outbreaks in schools, for example, were uncommon. This finding was accounted for in part by the fact that transmission of smallpox virus did not occur until onset of rash. By then, many patients had been confined to bed because of the high fever and malaise of the prodromal illness. Secondary cases were thus usually restricted to those who came into contact with patients, usually in the household or hospital.
and...
In addition, the immune status of those who were vaccinated more than 27 years ago is not clear. The duration of immunity, based on the experience of naturally exposed susceptible persons, has never been satisfactorily measured. Neutralizing antibodies are reported to reflect levels of protection, although this has not been validated in the field. These antibodies have been shown to decline substantially during a 5- to 10-year period.24 Thus, even those who received the recommended single-dose vaccination as children do not have lifelong immunity. However, among a group who had been vaccinated at birth and at ages 8 and 18 years as part of a study, neutralizing antibody levels remained stable during a 30-year period.31 Because comparatively few persons today have been successfully vaccinated on more than 1 occasion, it must be assumed that the population at large is highly susceptible to infection.
This finding was accounted for in part by the fact that transmission of smallpox virus did not occur until onset of rash. By then, many patients had been confined to bed because of the high fever and malaise of the prodromal illness.
This is of course accurate, but your mistake or misunderstanding is to overlook qualifying words like "many". It says "many", not even "most" or "the overwhleming majority".
There are documented cases where people who have not even known they were infected transmitted the disease to others. This has happened in people who are vaccinated. It has also happened with people past the initial flu-like stage and oral rash stage.
Since you like argument by authority so much I will provide a quote from a book.
When outbreaks were suspected, patients exhibiting symptoms of a cold and fever were confined because they were at their most infective, just before a rash broke out.
From Microbes and People: An A-Z of Microorganisms in Our Lives, Neeraja Sankaran, Oryx Press, 2000
In our previous discussion this was cited, but you simply don't understand the science behind it. Most DNA virus (eg cold and flu) share these properties because at the stage of viral replication where symptons are about to break or have just broken out, that is the highest level of virus in the body over the course of the disease. As cited in the prior thread, with small pox, that is the time of highest titer in the saliva.
After this point, in viral diseases, the immune system begins to get the upper hand and the virus is neutralized. This statge of infection brings on classic cold and flue symptoms of stuffy nose, mucous etc... which result from the infected cells being destroyed and sloughed off.
Small pox is of course different in that it is much more severe, but the dynamics of DNA viral infection are consistent.