One cannot provide AGPLed software to their customer without releasing the whole service code under the same license. Like, one cannot build cloud complier/linker to process one's customers' code. But one can link their compiled code using this linker and then sell that binaries or employ them in the SaaS all right.
One guy handling support doesn't stop them from using the product on Linux, does it?
Dev is the best quality in the world, as I said. I mean, there's no one who could be better.
If it's cheaper to build by themselves, why they didn't to that already?