No need to look at that datasheet. It's simple math.

If you have a PIC with a 40mhz OSC, then the processor is running at FOSC/4, or 10mhz.

Now let's say you want to make a clk output that's as fast as possible. It will take a minimum of 4 instructions. One to turn the Pin ON, one to turn it off, and a GOTO (2 cycles) to create a loop.

Those 4 instructions, just cut that 10mhz down to 2.5mhz, and it's only creating a clock signal. Now start counting 8-bit's at a time so you know when to get a new byte, getting the new byte from memory, and rotating it so the bit's can be sent one at a time, and you should see that there's NO way to bit-bang a 10mhz SPI data rate.