He's going to have the helmet off 90% of the movie

I don't think his acting style would work well as a lead for a tongue in cheek Starship Troopers style movie. As part of a four person ensemble where he isn't the focus it could work, but to be honest any tall and beefy action movie actor is going to undermine the tongue in cheek themes of Helldivers and is a strong sign that the studio is going to take a star studded cast approach like they did with Borderlands and the result will most likely be the same.

If this was an announcement that included three other actors/actresses who would clearly balance things out, like the cast of Dune did, it wouldn't be as concerning for me. Announcing a single person implies a leading role and he isn't the right person for doing that in a Helldivers movie.