Summary:
Generally one may not bring a קרבן without performing סמיכה, except in (rare) cases like ערל וטמא where there is no other choice (or if it is a ספק קרבן).
And it states they may marry off his wife - וקתני ישיאו את אשתו
Summary:
We can either establish the ברייתא before it was signed by פורסי שנמג, or we can say that we do not apply the rule of מסיח לפי תומו נאמן, by יוצא ליהרג (only by נהרג).