This hit absolutely was a penalty by the letter of the law. You want to avoid those hits. What bothers me is the announcer saying Mertz was tough for taking the hit, being fine and staying in. The thing is its not a matter of toughness. IF you have a head injury you should never stay in. The level of hit does not determine if you are fine. That attitude towards players who are injured during a play is what creates CTE. The culture that says your loyal or dedicated based on whether you stay on the field.