I'd make three simple points:
1. This is not just a case of well-informed experts versus shouty, headline-seeking campaigners. UNESCO, numerous archaeologists, and the Government's own planning executive are entirely against the short tunnel but have been ignored. [See for instance this withering statement by Rescue: https://rescue-archaeology.org.uk/2020/11/rescue-says-a303-stonehenge-dco-granted-a-sad-day-for-our-archaeological-heritage/?fbclid=IwAR2wT2m-Vndieuucgl5Yi5_Rd4hb_c668munXlCallO44vf8-I3LaPITGqI
2. This is a road project, not a conservation/improvement one. It is being painted as the latter by NT, EH, and HE only because the Government asked them to.
3. This could all be solved at a stroke by spending more money on a longer tunnel.