Members of the Service Employees International Union gathered outside Twitter's Mid-Market headquarters yesterday, with one protestor carrying a sign that read "Don't Twit on Me."

The SEIU was there to object the fact that Twitter and Square both use "the famously anti-union contractor Security Industry Specialists (SIS) to provide security services," reported SF Weekly:

Labor activists have waged an aggressive campaign against SIS for years, arguing that it keeps security guards part-time, denies them medical benefits, and actively prevents them from unionizing.

That may be typical of an hourly wage contractor, but it's anathema both to the culture of San Francisco and the rhetoric of Silicon Valley, where phrases like "Don't Be Evil" represent ideals as well as marketing credos. As Twitter gears up for an IPO that will likely value the company at more than $10 billion, it's under increased scrutiny from outsiders. Some criticize the company's lack of stewardship in its community, given the series of tax holidays that San Francisco offered to keep it headquartered on Market Street. Others say Twitter has failed to spread the love to its lowest paid employees.

However, like Twitter's $22 million tax break in exchange for questionable charity efforts, the protest, which appeared scant, didn't get anywhere near as much attention as Twitter's plans to more than double its footprint in the area. Bloomberg reported last week that Twitter wants to lease 320,000-square feet of office space at an estimated price of $15 million to $18 million annually.

I've reached out to an SEIU representative to see if Twitter or Square have responded to their concerns and will update the post if I hear back.

To contact the author of this post, please email nitasha@gawker.com.

[Image via Twitter/@a_s_h_o_d]