Maybe he really was in Houston when he called. The cities are only 3 1/2 hours apart by car, less than an hour by plane.
Not remembering where he was doesn’t sound plausible.
According the the “Memorandum,” GHWB called in his “tip” from Tyler, Texas, which is a little more than an hour away from Dallas. I’m not saying he was, but he might’ve been able to be at Dealey Plaza in Dallas at 12:30 pm when JFK was hit, and driven to Tyler in time to call at 1:45 pm. Or he could’ve made the phone call claiming to be in Tyler, when he was in or near Dallas.