It is completely valid to compare 2 bands. Thats how music criticism works (for that matter, any type of criticism in art)
This band is essentially writing the same songs that Pianos already wrote on their first 2 albums. Meaning they are not writing original music. The lack of originality can be used to form the opinion that they are not as talented, therefore not as good.
So if you go by that, then Rescuer is a rehash of a band that is a rehash of Touche Amore's older albums, which is a rehash of Converge, etc. etc., I just don't think it's fair to constantly repeat this cycle, because no one is original if you go by your standards. People do some inventive things (PBTT doing this in strides with their new stuff), but at the end of the day, originality is a "myth" that people speak of, but never really existed in the first place.
I should say that PBTT is basically my favorite band right now, I just think judging Rescuer solely on if they're as good as a band that influenced them. I understand critiquing bands with each other, but you're initial argument seemed like you are dismissing this band based off of one comparison, when, at least in my opinion, there is a lot more to judge a band on.
But, to each their own.