Here's what the article actually says:
"Mt. Gox estimates it costs $25 million in the first year to become fully compliant in the US. But considering a regulator could potentially swoop in and seize funds if a violation were found, its worth it."
Doesn't say that they actually did it, just that it's worth it to do it. Also, if they actually did it, they wouldn't have to estimate right? They would know exactly what it cost.
Funny that they admitted they knew exactly what the risks were, but still never followed through and actually took care of it.