A step parent is the same as a parent, for tax purposes.
He does not need to report the income, unless you are claiming the dependent care credit (DCC) for the money you paid him. Even then, he may not need to report it, if he baby sat in your home and he made less than $12,000 total income for the year, including the taxable portion of social security disability income (SSDI). You do NOT need to provide him any form (W-2 or 1099-Misc). It is not tax evasion*. If you are claiming the DCC, some people recommend that he file, even if not required, so your returns match up on the IRS computers.
*If you are not claiming the DCC, you can treat the money as a gift and not wages. Even if you treat it as pay, if he does not meet the filing threshold, he is not required to file
