MEXICALI, Mexico — Fifteen minutes into a heated session on whether bullfighting should be banned in Baja California, legislator David Ruvalcaba proposed that the fate of the controversial but financially attractive sport needed further study. Boos rang out and half the crowded walked out. For the third time this year, the Congress of the Mexican state of Baja California blinked in the face of banning a sport that has deep cultural roots in Mexico but is increasingly viewed as animal cruelty. On Thursday, 12 legislators voted for the delay, eight opposed it and two abstained.