So you give up performance by increasing bond allocation, you give up returns due to higher cost, and in return you get an insurance aspect that protects you from a tiny fraction of a risk. Sure, that insurance has value, but not the amount of value you would be paying in the lost performance and higher cost. I would skip it.
We know how the fund offers the guarantee, they just pay an insurance company to do the actuary math, and then insure them for that risk. So we know the odds are against you, the insurance company wouldn't offer that insurance without knowing they will make money. If the insurance you get from that fund was valid insurance to buy, why don't we all go out and get that insurance? The actuaries aren't hard to figure out the risk, and insurance companies would love the business. The reason is it's not worth much, and you wouldn't buy buying it except that you see it as a benefit without much cost. But if you actually did the math on decreased returns and added costs, you likely wouldn't be spending the money on that insurance by using those funds. It just feels free or cheap, but it's not.