REPORT ON BANK STIRS AN UPROAR
Uproar caused by Fed Reserve Bd denial of Banker's Trust NY Corp's proposed acquisition of First Natl Bank of Mexico (NY) because of reptd 'financial difficulties' of Bankers Trust; bd later issues statement, following outcry, declaring Banker's Trust financially sound and explaining that decision merely continued existing policy of denying acquisitions by banks that have been under financial pressure; some analysts believe bd blundered in choice of words, others believe bd intended warning to other banks to pursue acquisitions less vigorously; bank chmn Alfred Brittain 3d illus (M)