Some of the vendors in the iTC have concerns about antitrust violations while participating in the iTC.

Antitrust concerns should not be an issue for any iTC, since an iTC is more akin to a standards body than a trade group. To help ease concerns though, it may be helpful to open meetings (or presentations) with a review of an antitrust agreement for the iTC. A sample antitrust statement can be found here: https://raw.githubusercontent.com/itc-wgtools/iTC-docs/master/Antitrust.txt and is also included in the GitHub iTC Admin template repository.