[ceejayoz]

Maybe the guy despised corporate bullshit, but entered a Discover-sponsored sweepstakes or something similar that had a like requirement.

Or, he had to like Discover's page to be able to post comments there bashing their corporate bullshit.

There are a number of explanations, and deeming Facebook to be faking likes based on "I don't think my dead friend would've liked this page" is a little tenuous.