There are differences in the applications.
Most domestic cars used "sealed" pressurised coolant systems, the Alde uses a vented atmospheric system, so is "breathing" the header's void space in and out.
Plus, the gas burner can presents some real corrosion control challenges, in running locally very hot and is by its nature an item with a relatively thin wall thickness, thus heat is not well dissipated locally, and there is little thickness to tolerate pitting corrosion. Add to that it is an alloy, so that in itself can present its own grain boundary pitting corrosion sensitivity issues.
As designers of systems requiring inhibited water cooling, we all make our recommendations on a whole raft of factors, here Alde's designers recommend that even using a true VW TL 774 J, {short code, G13], the "safe" life is 5 years .
As end users we take our chances that they have called it right or wrong, we can bring in our own opinions, some reflecting features of our own use and make our own decision on ours. Me, albeit with quite a lot of insight into making such decisions on capital equipment cooling systems, I simply follow Alde's than try to rethink it all out for myself.