What is the reasoning behind setting MAX_SCRIPT_ELEMENT_SIZE to 520?

[sarva]

In script.h of the current Bitcoin Core client, the maximum size of an element which can be pushed on to the stack during script execution is specified to be 520? It was apparently changed from 5000 to 520 in the commit https://github.com/bitcoin/bitcoin/commit/4bd188c4383d6e614e18f79dc337fbabe8464c82#diff-8458adcedc17d046942185cb709ff5c3R425

I can imagine the limit is there to prevent some DoS attacks. Why the magic number 520?