Are curved aluminum forks safe?

It depends on how the fork is engineered for safety. While its plausible that the curved shape does add to some shock absorption, that is determined by the width and construction of the fork tubing. You could design a fork which was reliable and curved in aluminum or carbon or whatever, but the engineering wouldn't be the same as a steel fork. Whether the fork on that bike has been designed appropriately or not, is a different matter than if its possible.

You usually see it only on steel now, but older aluminum bikes have had that style (even mountain bikes), especially from Cannondale:

Jamis's Quest Comp Femme (and other bikes in the Quest line) currently uses that style too, for a carbon composite fork:

That being said, poor quality (and dangerous) aluminum forks have been made (the Viscount Aerospace pointed out by Brian Drummond in the comments is one example).

As for whether or not to get the bike, its sounds like you're not all that confident in their engineering, and to me that would be a definite no on buying the bike. I'd rather spend a few more dollars on a bike than on a broken face. If the Trek 1.1 is out of your price range, either find something used and nice or look at other manufacturers you can trust (if you go to brands which are well reputed, but not Trek/Giant/Specialized, you can likely save a decent bit).