Q: Why do you need a variable annuity if the money is already tax-deferred ?
A: So the financial advisor can make a commission.

(SO, you know my opinion)

Are you CSRS or FERS ?
If were were covered under CSRS your pension is probably pretty good, so you may not need a huge amount of guaranteed income from the TSP portion, which is what this annuity will presumably buy you.

If you are FERS, then you probably need a larger portion from the TSP since the annuity portion is about half what you’d get if you were CSRS.

These are important considerations to figure out what advice to give.

How much income do you need from the TSP to supplement your Pension income from the Gov’t ?

Also, you asked whether to roll into a variable annuity or keep it in the TSP, but you have a third option.
You can roll it over into an IRA at any financial institution (e.g. brokerage, bank, credit union).