Some of the reasoning behind this is easy to see. Seagate has already made it clear that they are willing to sue SSD manufacturers for supposed patent infringement. How far they will get remains to be seen, but it's not likely they will make much progress with lawsuits considering the number of manufacturers developing SSDs. Because of this, Seagate might want to get a huge advantage over other SSD manufacturers, relying on SanDisk's technology combined with Seagate's already long list of enterprise customers.
This is just a rumor for now, but a very plausible one, and one that could impact greatly the adoption of SSD drives.