Woah there Kiltsrhott.
"Horse Colour Explained" is a book that is at least 13 years old. That is a long, long time in terms of genetics.
Nowadays, we are fairly certain that tobiano does not cause face white AT ALL. So any face white on a tobiano is caused by another white pattern.
Nowadays, we have a test for splash white, and it has PROVEN that splash horses don't have to have even one blue eye, let alone two. Also, splash doesn't have to create a bald face - it can create just a snip and still be there.
Also, testing won't rule out sabino in this case. Most sabino type markings still test negative for Sabino 1, which is the only mutation that has a test currently. There is a least one more type of Sabino that we are fairly sure is there, with some people theorising a lot more than just one.