No, Fredo didn't intentionally set up the attempted hit, and yes, Roth may have had access to him because of his being the brother of Don Corleone.

But also, had Fredo not been Michael's brother and Vito's son...then he would not have had that cushy job in Vegas, planning parties and driving people to airports and banging waitresses two at a time. He was a bumbling idiot and was afforded a fairly comfortable life because of the family he was born into. He should have appreciated that much, but did not. He truly didn't realize how stupid and therefore dangerous to the family he was (as most truly stupid people don't) and for that reason he had to go, and Michael was completely justified.

As has also been discussed here before, the Roth incident was not the first time Fredo went against the Family. He had been warned by Michael before. Just because he was now living at Tahoe and apparently remorseful at what he had done...it doesn't mean he had learned his lesson. Somebody as smart as or smarter than Hyman Roth could have gotten to him eventually. He was no longer of any use to the family. He had to go.

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