Conclusions:
1. Anything that doesn't have 2fa is leaking like a sieve.
2. The targeted company needs to implement 2fa for their Wifi as well.
Not mentioned, but I assume that their 2fa is using specialised hardware gadgets like Yubikey and not texts or totp, because else they could target the cell phones, and like everything else they are leaking, or they are attacking the cell phone base stations.
Final conclusion:
A network is as strong as the weakest link. In that case Wifi was not protected by strong 2fa and could be used to breach.
Depends on how you look at it. We have end-to-end security with things like https, so we don't need to worry about the links in the middle.
Final conclusion: Do not trust a device just because it happens to be on your local network.