I'd guess that the combination of the outlet strip and laptop produces enough leakage to the ground wire to trip the gfci. Why doesn't it trip the home gfci? Easy answer: The generator gfci has a lower trip threshold than the home gfci. More likely answer: Not being an inverter generator, the sine wave output waveform is likely distorted, resulting in the laptop and surge protector's leakage to exceed the gfci trip threshold. Forget the bonding plug. If the neutral wasn't already bonded, the gfci would never trip.