The Choice website specifically states that everyone is eligible for the Little Leage rate. If you want to be extra cautious, they even provide a printable "identification card":
http://www.choicesportstravel.com/pd...vings_card.pdf
http://www.choicesportstravel.com/littleLeague.jsp
Save on baseball team travel! Coaches, parents, family and friends of Little Leaguers® receive at least 15% off your next stay with Choice Hotels. But you don’t have to be affiliated with the game to receive the discount – everyone qualifies. Best of all, it’s valid for any Choice hotel, anytime.
And if you'd rather support the LPGA, there's a similar discount for all there, as well:
http://www.choicesportstravel.com/lpga.jsp