All my sidecars have stainless spokes . Sidecars raced in MX have huge sideforces when you drift them at speed over ruts . I never have a problem . But I have seen people collapsing wheels again and again....
it looks like collapsing wheels has nothing to do with the material , but more so how good you build the wheel. It is correct stainless can get bridle by bending , but then think closely , if a wheel moves and flexes that much to cause that , it was not built correct in the first place .