The language of CISPA explicitly prohibits the government from using such protections to force companies to give up data. Again--read the EFF article. It does not even use the phrase "law enforcement" at all, nor the word "force". The only usage of the word "power" refers to the power of private companies to collect data related to cybersecurity (which of course they already do).
The EFF is right to raise questions about privacy in the context of cybersecurity coordination. Where I part ways with them is that they seem to have taken a maximalist approach that any and all sharing of data is wrong and should be prevented. I happen to think that there is a role for the federal government to help coordinate cyber threat information.
If after CISPA, federal agencies can receive more private data than before – in ways that were previously prevented by liability under the Wiretap Act, the Stored Communication Act, contractual obligations, and other court precedents about expectations of privacy – then that's a 'new power' for law enforcement. Even if the way the new power is created is indirect, through immunized information 'sharing'.
Your argument doesn't pass a simple-logic smell-test: why would law enforcement want this, if it doesn't give them any new capabilities?
Organizations that are expert in the legal implications of such bills, like the EFF and ACLU, disagree with you about the effect. Their concern is that under CISPA, "these combined power and immunity provisions would override existing privacy laws like the Wiretap Act and the Stored Communications Act." [1]
Imagine there were a law which said, search and seizure without a warrant or probable cause is bad, but any evidence so collected is always admissible in court, and law officers who collect such evidence may never be disciplined in any civil, criminal, or administrative fashion. That creates a de facto new power, because it shifts all the incentives, and agents may then search and seize with impunity.
The concern of the EFF and the ACLU is that CISPA does something similar. It sets up a system where doing the federal government the 'voluntary' favor of sharing information -- even in contravention of other laws or contracts that could create liability -- is always the safe and easy course. So, agencies wind up collecting far more info that people expected to be private.
There's an old joke that "national security" is the root password to the Constitution. Well, CISPA makes "cybersecurity threat" the root password to every private service-provider data set.
[1] https://www.eff.org/deeplinks/2013/02/cispa-privacy-invading...