I have got to say, i think that is nonsense.I'm not suggesting that pork shouldn't be used in a pie, just that using pork mince to emulate shepherds pie will result in a pitiful imitation.
SIMPLE PORK MINCE COTTAGE PIE
https://markieskitchen.com/simple-cottage-pie-recipe/https://www.riverford.co.uk/recipes/swineherds-pie
https://sunporkfreshfoods.com.au/recipes/pork-sheppards-pie/