I2C monitoring without Microcontroller
I'm not sure there is an existing product that does what you want. If you were going to design a custom solution, some options might include:


Use programmable logic such as a small CPLD to implement the I2C interface and have a state machine track bus activity to capture the data you want.
Like #1 but use a dedicated chip such as the PCA8584 (I2C to parallel bridge) to do the heavy lifting for the I2C protocol and have a CPLD handle the higher level activity monitoring. This chip has a snoop mode where it is guaranteed to not drive anything on the I2C bus and monitor it non-destructively.
Use a microcontroller with a similar I2C snoop mode such as the LPC1769. I don't know if having this functionality implemented in hardware (on-chip) would let you circumvent the regulations about software however, since a software bug could take it out of snoop mode and introduce erroneous I2C traffic. So that's a bit of a stretch.