Are you sure that even HAS an I2C interface??? SPI and I2C aren't hardware or software compatible.
I2C is inherently two wire where an "Ack" is used whereas SPI is pure serial using three wires where two "MISO and MOSI" are a ring connection.... You would need to re-write the firmware on the Wifi unit... If you tried the connection as you need, the data return would be though GPIO 7 and as it is simultaneous it would be impossible to read the answer whilst transmitting the question..