It's not only N2. A reaction which only works under N2 usually also means `requires rigorously dried solvents, dry N2, no traces of water whatsoever, or else you're fucked'. You just can't solve that by flushing a bit with He. Unless you are trying to do LAH reductions in a US state with over 100% humidity.
When all you've got is a nailgun, every problem looks like a messiah...