Take it.
I hate flag, but coaching five-year-olds for a year will help you a ton.
As Einstein said, if you can't explain it to a six-year-old, you don't understand it. (I don't know where he stood on explaining things to five-year-olds.)
You will get WAY tighter with how you look at things and how you explain things. You can be really sloppy with older kids (and adults) and try to explain away contradictions and inconsistencies and that sort of thing. With five-year-olds, it needs to be really clean and sensible, the first time, or you have no shot. Confuse them the first time you try to give them something, and you'll be paying for it for weeks.
Look at it this way: Could the average boss in the workplace lead a bunch of five-year-olds? Hell, no. It takes adults to figure out what the boss meant, what he didn't really mean, what was just talk, what was explained incorrectly, etc.
The two years I coached little dudes helped me a ton.
Count it as a one-year investment in becoming a better coach.