I run my 28C Continental Gatorskins, rated at 120psi at 120psi on my road tandems (aluminum and steel). You are perfectly fine running a bicycle tire at "Max" pressure, assuming industry standard parts and proper installation.
I know some road tandem teams who exceed the max pressure on the sidewall by about 20 psi. I don't do this, nor recommend it. But people do it.
However, today there's a move to much wider road tires. Avoiding harsh riding and improving comfort are the usual reasons. And several tires have been shown to have lower rolling resistance at lower than max pressures. (The historic assumption was that the higher the pressure, the lower the resistance. Not necessarily true.)
But avoiding pinch flats and rim damage should be your main concern on a tandem. Since they carry much more weight, tire pressures historically were always at the high end. But again, today's bikes with greater tire clearance allow wider tires, which require and function well with lower pressures. Better for off road performance as well.