Such experiments on scrapie were performed as far back as the late 1960s (Nature 214, 764-766) and a large body of work leading to a relatively conclusive answer was carried out prior to the late 1980s.
Knowledge of the nature of the agent does not tell us whether it is infectious to humans. Species barriers preventing the transmission of spongiform encephalopathies between species are present in some cases but not others. Chimpanzees appear to be susceptible to CJD but not to scrapie whereas goats are susceptible to CJD and to scrapie (Cell 40, 735-746). These results and many similar were known by the early Eighties. It seems hard to see how the Government could have ruled out the possibility of transmission of BSE to humans.
Experiments are being carried out in which genetically engineered mice carrying the human version of the prion protein involved in susceptibility to the disease have been exposed to BSE (Nature 378, 779-783). These experiments need to continue for a number of months before conclusions can be drawn. The construction and testing of the mice strains used was reported in 1994 and would have been the results of at least three years of work
Your editorial also says that "it is all very well for visionary scientists such as Richard Dawkins to deliver us accounts of what makes us tick. It would be more useful if science was more open to the questions we need it to answer." Only a small fraction of research funds and time are spent doing the type of research popularised by Professor Dawkins. Most research does consist of exactly the sort of "grindingly boring" experiments your article suggests need doing. It is worth asking what the market would have been for a popular book discussing the dry facts of spongiform encephalopathies prior to the BSE outbreak.