Lets take this apart, legally that is.
"flooded with bogus files -- all coming from sources that can marshal massive amounts of bandwidth and banks of computers occupying a narrow range of Internet addresses"
Would it be legal to set up a web site that tracks users reported to be sharing "bogus" files, like those people who record their own band's song but name it something popular?

"they're evaluating other technologies that would scramble search queries"
Now we know where those queries are coming from, see above for bogus IPs. Aren't they disrupting a computer network? Isn't that illegal under THEIR current law? DMCA?
Should we start logging this activity?

"Those countermeasures could cross 'into a gray area as far as legality,' admits another record executive"
Gray? Isn't sharing for NO PROFIT gray? Wasn't copyright created for people making a PROFIT from selling bogus CDs? They used to say the damage was "customers get a low quality product"?

"add file attachments to make a compressed music file" - larger than a cow.
No one would be that stupid.

If you do get a "bogus" MP3 directly from one of those known record company IPs, then can't you consider that their official SAMPLE PRODUCT that they are giving away and thus THEIR SAMPLE PRODUCT SUCKS (and the band that is named is then damaged)?
Could someone legally spread that sample file all over to help those poor, hungry record companies with their public relations? They need our help guys, come on, help out would ya?

"electronic countermeasures intended to frustrate the 18.7 million consumers"
Frustrate your customers, current or future, now there's a smart new marketing concept.

"It's clearly intended to disrupt the file-sharing network"
Let's re-word that to DAMAGE the network and those who are using it, and thus it's illegal, plain and simple, with or without DCMA or "congress approval". Damage is common law and we never gave the government authority to license people to damage other people.

"Some label execs say they're evaluating other technologies"
Hey, before I call my lawyer, I have a technology for them that's easy to do:
They should LOWER THEIR PRICE so low no one will want to bother with sharing networks. Never mind, too simple.

Anyone at the EFF ready to take on this case?