I'm trying to allow the author of an entry to be searchable using expression engine's simple search form. Is this possible?
It should be possible.
Using EE's stock advanced search form you can include a "member name" as a free text search field, see http://ellislab.com/expressionengine/user-guide/modules/search/advanced.html
If you wanted to pull in precise names you could look at using a plugin to pull a list into the search form, eg https://exp-resso.com/freemember - there may be other plugins you could use at http://devot-ee.com - failing that a simple SQL query should do the trick.
Failing that Solspace's Super search modile - http://www.solspace.com/docs/super_search/search/ - has the ability to include author information in searches.