That's a mischaracterization of the article.
The article points out only that Reagan submitted budgets that projected lower spending on entitlements than actually came to pass, because he projected greater economic growth and lower unemployment--the "rosy scenario". Neither congress nor the president appropriates for entitlements; rather, they are authorized programs for which spending is mandatory. Nothing on that page shows whether Reagan proposed cuts in entitlements (which he generally did) or what congress did with those proposals (generaly reject them).
Where it's interesting is discretionary spending. Reagan dramatically shifted the patterns. He decreased most discretionary spending (or sought to), but massively increased defense spending. Proposed versus enacted would be much more telling in that area.
