[teraflop]

The whole point of trademark law is that the owner of the trademark gets to control how it's used in commerce. If the mark is being used to advertise a company's product, grsecurity has the right to prohibit it; the company doesn't get to make the call.

This isn't a free-speech issue -- it's just a simple acknowledgement of the fact that consumers treat names, logos, branding etc. as indicators of a product's origin, and that there's a public interest in making those indicators accurate. You can refer to the trademark as long as you don't do so in a way that misrepresents your product. In this case, unless there are specific disclaimers to the contrary, a reasonable person would think "grsecurity" means "code released and approved by the grsecurity team", instead of a version that a third party has modified.