More than likely, this logo just looks better than a t-shirt that reads, Untitled Han Solo Star Wars Anthology Film.
Having said that, this would totally work as the film’s logo, a simple Solo with a blaster in place of the L is a great image.
While this is unlikely to be the movie’s final title, since we’re assuming that Han Solo’s name will be in the title of the movie someplace, seeing the blaster used like that in the official title is certainly a possibility.
To be clear, this is a logo that is being used on shirts worn by the crew of the film and it’s highly unlikely that the image here will be used for the film itself.