La diferencia entre so y such ya la hemos explicado aquí. Al usar estas partículas de comparación con un infinitivo se debe añadir el infinitivo con to.

Presentacion de forma esquemática   so + adjetivo + as + to + infinitivo   such + sustantivo + as + to + infinitivo

Ejemplos   He is not so stupid as to eat this food.   We are not so tired as to stay home all evening.   She is not such a fool as to give you money.   They are such thickheads as to understand the good idea.