> The reasons for this seems to be that bats are just too small and the virus load too thin to pose a threat to humans. So bat to human is very unlikely, but bat to cat is more plausible, and then cat (etc) to human also more plausible.

Some bat species, e.g. flying foxes are not really small and can weigh about 1 kg. Also bats are very strange that they can tolerate high virus loads without getting ill. There is a report that one of the Chinese researcher got infected while collecting samples.