I have to agree.
Although I was really impressed by the clever word-play to see an association with Baptism and the Eucharist made! That was something I had never thought of before. I am always excited to see a completely new interpretation of a passage, and it reminds me how much our own beliefs and background shape our own interpretations. Here where some Protestants see their own beliefs of "faith alone", some Catholics see their own beliefs about the sacraments!
I agree there's no obvious connection to the Supper here. But interpreting it as blood sacrifice is also problematic. There's no other reference to sacrifice here (unless one interprets Hilasterion as sacrifice which seems rather dubious). Rather the extremely strong parallels between this verse and the Jewish Martyrdom account of 4 Maccabees 17:21-22 point to a martyrdom reading of this verse (as does Paul's general love of Greek martyrdom terminology and his other references to martyrdom within Romans, eg Rom 5:6-8). ie the word "blood" seems to be a reference to Jesus' martyrdom.
Agreed. For Paul, "works of the law" and "good works" seem to be very very different things. The works of the law are various rituals and ceremonial requirements, which Paul feels it is not necessary for the Gentile Christians to adopt, and which Paul is very negative about at times. Whereas good works are something Paul is always very positive about, and at times says are required for and cause salvation (eg Rom 2:6-8, Gal 6:7-9 etc).
I think one of the mistakes that got made in Protestant exegesis was to contrast 'faith' to 'good works'. In Greek the word being translated 'faith' is pistis which means faithfulness, obedience, commitment, and perseverance. To faithfully follow Jesus is precisely to obey his commands and do good works. Thus good works would appear to be included within the meaning of the Greek word for faith. To try to separate faith from good works is like trying to separate obedience from obedience and seems a bizarre approach to interpreting Paul's writings. (But then, a number of Protestant interpretive moves don't make much sense when you look at the Greek, which is probably why the Greek speaking Orthodox Churches never developed Protestant doctrine!)