The irony is that the entire NDB approach could have been flown in LNAV/VNAV. Or, worst case LNAV/VS, whilst backing up the Descent page guidance with timing from the approach chart. And the ADF confirming the LNAV guidance.
I think you will find their SOPs say that if the approach is not "coded" in the FMC then it is not permitted to engage LNAV/VNAV to fly the approach, or words to that effect.
I'm not saying I agree with that but that was certainly the case when I was with said airline some years ago now.