Congratulations on your husband's "almost there" retirement.
As Iam mentioned, I believe you can leave the funds in the TSP. However, their withdrawal rules do limit your options. You are only allowed one partial withdrawal. After that one, you would need to withdraw the entire remaining balance or annuitize it. It sounds like you don't need the income, so annuitizing it doesn't make a lot of sense. If you think you might make periodic withdrawals for some reason (vacations, car replacements, etc.), you're pretty much forced to remove the money from the TSP. If you don't think you'd make periodic withdrawals, then leaving it in the TSP is an option. Understand that the G fund may provide returns lower than inflation, so over time you will lose purchasing power.
If you do roll it out, move to Vanguard (or a similar low-cost option). The greatest plus of the TSP is the low fees, and Vanguard comes really close!
One other idea to consider: If you never anticipate needing the money (as your income is coming from other sources), you are really saving it for your heirs, who may be much younger than you. If so, you may want to consider investing a portion of it in the stock market. I fully understand you have a low risk tolerance, which is perfectly fine! But if your heirs are younger, their time horizon may be so long, that equities make the best investment option. Of course, if you want to leave it as back up plan for your financial needs, invest it in accordance with your risk tolerance and need for risk.
Good luck and let me know if you have any questions about my reply.