I think that servicing 98% is not the same as 98% market share, and that anti-trust cares about market share. All it means is that 490/500 companies bought at least one Dell/EMC product. I'd assume most also bought at least one IBM/HP product too.
They're not necessarily the only company those 98% use... I'd guess that Dell is already a supplier for at least nearly that high of a percent in some regard.
In the end though, just because you have a near monopoly doesn't mean you're violating anti-trust. EMC already had that reach, even without dell.
Dominating the market is not illegal - anti-competitive behavior is. The former is still possible just by being really good at what you do and how you sell.
Not to mention that nobody claimed that EMC was the only supplier for 98% of the market. As a similar claim, RedHat[1] state that 100% of Fortune 500 banks, airlines, telcos and healthcare companies rely on RedHat. Is it a correct statement? Probably. But does it mean that RedHat exclusively sells to 100% of those markets? Of course not.
How is this not an antitrust issue?