There's a bit more to it. The reason vaccines weren't developed previously for other coronaviruses is because in trials for a RSV vaccine, 80% of treated kids that got infected needed hospitalisation and two died, while something like 5% of the control infections needed hospitalisation. Due to antibody-dependent enhancement.
So yes there are immunopathology concerns with eliciting a T-cell response, and inducing a humoral immune response has the potential to make things worse.
That's why most trials take a look at the Th1 vs Th2 response to see if there's any indication of ADE. The currently available data do not seem to point to that.
So yes there are immunopathology concerns with eliciting a T-cell response, and inducing a humoral immune response has the potential to make things worse.