[mannykannot]

While this technique allows an attacker to avoid revealing the exploit if you simply redirect the curl output to a file, it will contain tell-tale information (in this case, bufferloads of zero bytes) allowing one to discern that it is up to no good.

The author hints at other techniques for detecting curl|bash (http or dns callbacks), which would obfuscate but not completely mask the attacker's intentions.

Note that I'm not advocating for using curl|bash: it's a technique for gathering low-hanging fruit, and there's no point in putting yourself in that position.