I don’t agree. Most merit awards are a flat amount, like $20k offered to Presidential Scholars, or those with a 3.5/32 ACT, or a chart of which stats get $$$ as merit. There are some merit scholarships that have a need component, but IME those are the smaller amounts, like $2000 to a nursing student with ‘need’ and ‘need’ is not defined. A school can do anything it likes with its own merit money, but I just haven’t seen a lot of merit that considers need.
Could you put the bonus into a 401k or IRA directly from the employer? Yes, that would be added back into the income for the FAFSA but it is going to be income for FAFSA anyway. If you haven’t maxed out your contributions, that’s one way to get it into retirement funds. You’ll save the taxes but it will still be income for 2019 FAFSA purposes.