Musk is not in a position to identify waste and fraud.

What does he know of the genesis and status of these payments? Congress directs spending and oversees the administration, not the other way around.

Why does he have to finish in an arbitrary time frame?

This is all justification after the fact for those who support Musk/Trump unconditionally.

It's all fun and games until your Medicare/Social Security/Tax Refund or other legitimate payment gets cancelled arbitrarily, illegally and unconstitutionally.