Anti-trust issues would not stop EMC
If EMC wanted to buy NetApp, anti-trust concerns would not block the acquisition. EMC and NetApp combined would still have significantly less market share in the storage market than other IT companies have in their markets (Cisco? Microsoft? Intel?) and those companies have not had any major anti-trust problems. It's stupid for Warmenhoven to think an acquisition couldn't happen because of anti-trust; it wouldn't be an issue at all.
The truth is that EMC isn't interested in buying NetApp, primarily because EMC execs are genuinely just not all that impressed with NetApp. I can understand why Warmenhoven didn't cite that as the reason.