@pchong90 2 problems:
1) this option should not even be available if TA is not given
2) it probably best to enable new implementation by default, if available. I.e. 
#if defined(HAVE_MPQC3_RUNTIME)
  opt.enroll("mpqc3", GetLongOpt::MandatoryValue, "enable MPQC3 runtime features; default: true", 1);
#endif