Most likely, he'll want to roll it into his 401K or into a tIRA. You didn't mention tIRA as an option, but it almost certainly is.
There are a couple of somewhat uncommon issues that might apply to him. The first is to investigate how good of a deal the annuity offering is. It will depend on if his pension is structured as a cash balance or defined benefit. If it's defined benefit (the most common type), then what he'll be offered is just a replacement annuity for the benefit he has vested. If it's a cash balance plan, there is a chance the annuity offered to him might be a better deal than available retail. If he was inclined to consider the annuity, that would be a factor in that choice's favor. Unlikely, but not impossible.
The second issue that might influence his choice of tIRA or 401K rollover is if he (they) earn over the MFJ limit for direct Roth contributions ($236K in 2025 for MFJ) and they have cleared all traditional IRA balances without basis. They would have done this to make backdoor Roth contributions. Uncommon, but possible. If that is their situation, or may be their situation in the future, then rolling into the 401K is the right choice. Otherwise, all else being equal, rolling into a tIRA at their favorite brokerage is probably the best bet.