If you are using the trademark to make a political statement, then that is fair use
and there is no infringement.
If you are using the trademark to sell some other product or service in preference to the trademark, and that trademark is recognizable to an ordinary person, regardless of the pixelation, then you are at risk of being sued for dilution. In order to sue on this ground, the mark being diluted must be "famous." A famous mark is determined by:
(1) the degree of inherent or acquired distinctiveness; (2) the duration and extent of use; (3) the amount of advertising and publicity; (4) the geographic extent of the market; (5) the channels of trade; (6) the degree of recognition in trading areas; (7) any use of similar marks by third parties; (8) whether the mark is registered. 15 U.S.C. 1125(c)
Since this issue must be determined by a court, a large amount of the risk is determined by whether or not you are willing to pay to defend yourself, even if the mark is not famous. Defending a dilution lawsuit could easily run $10,000-$20,000 or more.
The easy way to protect yourself is to obfuscate the trademarks so that no person can reasonably identify the competitor(s).
Hope this helps.