Why are fans assuming that Burgess will step right in as a starter opposite Thomas? That's unrealistic... Admittedly, he'd said he's behind, has little experience playing at outside linebacker and is joining a new team. All things a fan could observe based on what you've read or already know about him as a player. He's a former two-time Pro Bowl selection but I believe that was as a DE. He's older and will be playing for a new contract. Certainly, the motivation is there to begin with. That's good.
I expect him to eventually start full-time at some point during the regular season. But that decision will come only when Burgess has demonstrated to Belichick that he has fully grasped the defensive play book. These things take time depending on the individual, of course.
From the interview, he seems like an intelligent (and perceptive) player and person, but appeared somewhat restless. But then, most players probably would prefer to focus on football and avoid the press if they can help it. No one really enjoys having microphones and tape recorders seemingly thrust near your mouth, sports journalist hanging onto your every words and reactions. It can become irksome after a while, you desire to conclude it. So I don't have a problem with how he'd handled this interview. He did well. He even injected humor at one point. Some of the questions were redundant. He likely heard them beforehand just by picking up a newspaper.