Are these two visions (digital gold vs. FPS) mutually exclusive?

That's what I'm arguing.

How exactly does increasing block size lead to a less secure network?

More centralization, non-full blocks and therefore less fees, therefore less incentive to mine, therefore less secure network.

Would an increase in block size make Bitcoin more susceptible to attacks or control by governments?

See above.

I don't see anything within the hard fork which prevents using out-of-band or mesh networks to process Bitcoin transactions .

And with how things are today?

If it's not broken, don't fix it.

This man gets it.