Earlier quoted context omitted.
Technically, couldn't he install a very lightweight Linux distribution. I have a few Raspberry Pi zeros and I actually enjoy coding within the limitations of said hardware, when you know you only have 500 megs of RAM on the device you have to solve problems differently
For some reason I find "only have 500megs of RAM" very amusing. Many/most modern laptops only have 8-16 times more RAM than that. I'm genuinely curious what problems you're working where that "limitation" is your bottleneck and not the processor speed (which at 1GHz is still pretty speedy for many/most tasks other than pure computation (e.g. machine learning training and processing large datasets for statistics)). I'…
To some extent, being careful about memory usage is not the only way to make the business work -- you could, after all, charge more for the service or make people buy the CPE outright. But, being an ISP mostly involves getting enough people to buy the service to make it worth digging up a neighborhood to run fiber; you don't want to sour the deal by costing more than the competition with less able CPE. Doubling the RAM available to software engineers may improve the user experience by more than 100%, but nobody picks their ISP for the software than runs on their TV box, so it's probably wise to be careful.
My point here is that some programmers do have to care about memory usage. If you include a computer as part of your product, you will someday be looking at the BOM cost of the bundled computer in an attempt to turn cost into profit.