It sounds to me like this (original) "inherited decision" was not made too carefully. If the bottom-line purpose of a particular box is "to run SAP," then as he said, "the OS doesn't really matter as long as it is stable," and of course, as long as it is certified by SAP. The box isn't there to run Linux, or Windows for that matter: it is there to run SAP, and to do it (as much as is possible with SAP ...
...) "in 'fuhgeddaboudit' mode." If one OS isn't delivering the goods, for whatever reason,
switching it makes perfect sense.
I agree that it will be interesting to follow-up with this organization in another
six months' time. The root cause of "an un-reproducible error" is not likely to go away. It probably will
turn out to be a hardware error... it could even be the fault of a sometimes-unstable power supply voltage.
The total cost of ownership (TCO) for software of any
type is, really, extremely high. It is often under-estimated, especially by contractors. In this case, the company's decision to "cut bait" is, imho and as much as I love Linux, justifiable.