[Etab]

Is the argument that Google doesn't index hidden text, or that Google penalizes the use of hidden text?

This experiment proves what we knew -- Google indexes hidden text; however, it doesn't prove or test what people want to know -- if Google penalizes results that hide text.

[nkozyra]

Yeah, ultimately this doesn't demonstrate anything. We know Google can index text if it's hidden - the only issue with hidden/obfuscated text is that if Google determines it to be so, there's likely an SEO penalty to be paid.

The searches done here are so explicit that all it's demonstrating is that pages that are indexed by Google exist in the index. We have no information on how that would compare against competition (poorly, likely).

And to boot, OP may have degraded his/her own blog's overall SEO.

In short: not very valuable.