If the employer gives each employee a chromebook instead of a desktop, and tell each employee to get Office on their own, then the employer doesn't have to pay license fee for every employee. I imagine this can reduce the operation cost by a lot.
How so? I can carry my laptop to my office and use my laptop instead. When I come home I get paged and my boss wants me to read a document. i wouldn't go back to my office just to open a document, would I? If I work for my dad's deli and I need to help him print a price tag I would be "working" for my dad and using my personal Office would violate the policy - but who would pay for a copy? I am self-employed and I use Office at home for both school, self-employed work and for personal use. Personal use is a very grey area - hence why personal edition has missing features.
The service/software may not be used for commercial,
non-profit, or revenue-generating activities.
While EULA do not always hold up in court I can't see a reason why this wouldn't hold up. What you should do is VPN into work to do something for your boss. Or even better have a enterprise licensed version on your laptop. Yes you are violating the policy when you work for your dad. Your example of a single, small user violating the EULA is far different than a corporation actively encouraging users to violate the EULA. You may not be worth suing but a company sure is.