ZDC Controller reported developmental issued incorrect missed approach instructions resulted in an aircraft entering a higher MVA and a CFIT event.

Narrative

Aircraft X requested alternate missed instructions 'climbing 3000 ft. then direct SBV'. The R-side issued 'on the go; climb to 3000; cleared direct to SBV'. We were training on the D-side and queried the R-side trainee as to if he actually issued alternate missed instructions. The R-side said 'yes'; and that the aircraft was to turn direct SBV reaching 3000. We pointed out the MIA was 2900 ft. and we heard 'climb to 3000 ft.; cleared direct SBV'. The R-side's trainer did not intervene to remedy the fact that alternate missed approach instructions were issued when the procedure is not allowed at DAN. Nor did he verify what altitude the aircraft would be turning direct to SBV on the missed. The aircraft checked in 'direct SBV' leaving 2100 ft. (estimated altitude). R-side trainer should have caught the mistake and then fixed the mistake as opposed to allowing the aircraft to continue on the illegal missed approach instructions. Both R-side trainee and trainer; were made aware of the mistake while we were still in communications with Aircraft X; before he even began his descent on the arrival. No corrective actions were taken. Since no corrective action was taken; I am uncomfortable working the D-side of this particular training team.