The ad argues that it is the patriotic duty of Americans to call out potential Communists (who will "usually deny that [they are] Communist[s]"). We must take action, says the Timken company - and on a larger scale, the American public.
While the Scot Tissue ad was chiefly worded as an appeal to employers, this Timken ad goes further. The Timken company has brought the capacity to do justice to the entirety of the American public (take that, Batman!), and as such, has placed an enormous responsibility on the public as well.
Now, if you'll let me get off topic for half a second, I want to talk about the fear-mongering that's going on in this ad. The Scot Tissue ad didn't inspire nearly as much terror - rather, it offered a form of protection. The language used in the Timken ad, however, really puts the "scare" in Red Scare.
There's a similar kind of fear-mongering going on today in mainstream media about...well, about almost everything. Global warming is the end of the world! Snowpocalypse! Terrorism! Snowmageddon! The government shutdown! Snowquester! (And that's not even to start on the harsh racial undertones that are carried by one of the networks that basically rules the fear-mongering market - looking at you, Fox News.)
Fear has become an acceptable method of journalism, and I think part of that may have come from ads like this Timken one being run so frequently in the 1950s.