good idea to keep at least one share but unlikely to be a SPP and more likely to be a rights issue.
For every 1 share you hold in BBI you will probably get 10 rights to new shares at the heavily discounted price. Therefore the more shares you hold the more rights to the new shares.
My view is that the risk of the banks tanking the company is low. It has a 2x interest cover at the corporate level and they know an investor is at the table.