I don't think so, the lever blade is not in the load path for the tightening to the handlebar, I think it cannot be stressed by tightening that bolt.
Are there any new alu alloys used on bikes since the '70s? They had 2024 and 7075 back then, I haven't heard of anything stronger, though I am not an engineer, no finger on the pulse of the alloys world.
Weinmann used a very ductile alloy because their brakes and levers are forged, basically shaped by smushing, so they have to have a high capacity for smushing. Also, the strongest alloys no doubt would be avoided for cost reasons. But for surviving crashes, I'd rate the Weinmann right up there with modern alloy levers, probably better than lots of them. Campy old Record (sometime erroneously called NR) levers were more more likely to fracture in a crash than Weinmann. The blades are tough but the cast "perch" is brittle. Weinmann were tough in the perch as well. Probably 5x as tough as the old Universal 61/68 levers, though those can be broken if you sneeze too hard.

The ductility of Weinmann stuff also allows you to safely straighten them after a crash. I think they chose their alloy very well.