Using mason jars will not be as good as using flexible packaging. Both hand pumps and food savers only create a partial vacuum, so only a percentage of the air is removed. With the mason jar, there will be a greater amount of air left in the jar since it's inflexible and a larger fixed volume compared to plastic/mylar packaging which changes shape and compresses the hops together, reducing space between the hops and between the hops and packaging.
Removing the oxygen helps reduce the rate of oxidization. So I think this technique will work, and work well, just not as well as using a mylar bag.
You will get much better preservation of the hops if you freeze them (with or without a vacuum), rather than storing in the fridge.