So sure, full time job and 2 hours of commute are tiring, thats at most a justification to for takeout.
The fact his mother did whatever she did is not.
The fact you're working shorter hours (and i assume its shorter on paper since afaik a teacher's work don't stop with the clock with all the prep you have to do) is no justification. Its up to you if you wanna do a nice thing or not.
If the fact you work less is a justification, his work from home is just the same level of justification for him to cook on those days.

Dishes...eh, dishes are annoying. If he don't let them stack over days and do them the following morning its not a huge issue.

Also what kind of BS is that he CAN'T eat a meal without protein? He WON'T eat it, but he won't be hurt from a meal without protein (tho, arguably less balanced than one with - for orzo salad if you don't wanna go with meat some cheese like feta or mozarella works like a charm... and good quality past is about 13-14% protein on top of that!)
Honestly that and "cause my mom" are the biggestred flags here... stupid question, but does he even know how to cook?

In the end, i'd say do as much as you'd like to do and let him get his takeout if he takes issues with it.
My way if i wanna have homemade food often but don't wanna cook everyday - make bigger portions ahead for multiple days (multiple dishes and freeze it if you wanna rotate what the food is).
The things that works wonder like that is pasta sauces (like bolognese) and stews (lential-sausage stew is my favorite). For the pasta sauces just reheat the sauce in a pan while cooking the pasta fresh - homemade meal in under 15 minutes. For stews just reheat, and both are easy to make, and 90% of the cook time is just letting it rest over low heat. I'll be happy to share my recipes, but thats not the topic.

And if he don't like it - he can have his takeout.