This came from HSLDA:
Because Texas does not have a law granting homeschooled students the right to participate in public school classes and activities, individual schools and schools districts have the authority to decide whether to allow homeschool students to participate. Policies vary according to district. On the other hand, Texas’ athletic association, the University Interscholastic League, prohibits homeschool student’s participation in UIL sports at the local public school. See the UIL’s eligibility policy: http://www.uiltexas.org/policy/eligibility
Looks as though Keller ISD can call the shots as they please.
If your son wants to compete, y'all can make your own club team and join the THSBA. Now, if your son's best friend attends Keller, he will have to fish for them, per our rules. If he is also homeschooled, simply fill out the membership packet for your own club. The membership packet can be found on the THSBA website, www.texashighschobassassn.com
and send it in to the address within the packet.
If you do in fact form your own club, you will still be required to follow all the academic eligibility rules, just as the rest of the teams that fish in the THSBA.
Hope this helps.