First of all, we don't necessarily know if it was ordered "in bulk" -- only that the Navy may have made an order of some steam cat components.
As for why they may have ordered steam cat components back then, that was in the post I linked...
"From my understanding the EM vs steam cat competition only really began 1.5-2 years ago and only really should have proceeded over the last year or so. If steam cat components were ordered years ago, that would likely be indicative of the Navy making the order for the steam cat components well before the EM vs steam cat competition began and possibly well before anyone first thought to do an EM vs steam cat competition at all."
In other words, the Navy may have placed an initial order because back then there was no tender/competition, and it was assumed that 002 would go with steam catapults. But then the competition happened.
If we throw our minds back to 2013/14, the consensus was that steam was going to be on the cards for the first 002 as well, and EM cat was still a distant and unlikely possibility, and the catapult competition was a surprise for us as well.