I hate to break it to you guys, but low delay is not the end-all be-all taunt for warriors. We have a level 60 warrior that recently acquired the 50/43 shovel, and he holds aggro better with it than with a jade mace. Aggro is a combination of many things, and delay is only part of it. The fact that you crunch something for 500+ points in a single hit (critical, of course) or for double hits of 330+ (non-crits) really pisses a mob off.
The reason, if there is any, that warriors might should consider passing on this or any other post-epic two-hander is not because they don't make great weapons, but because post-epic one-handers for warriors are even more awesome than this. The problem you will run into in most high-end guilds is that you can't simply roll on anything that comes down the pike and you can use. A warrior that opted to use this or even the shovel might very well find that he has to pass when a post-epic one-hander is up for grabs, because he already looted an uber two-hander, thus depriving a knight from using it. That is the reason warriors might want to think it throgh carefully. If they are okay with that, then this weapon would make a fine warrior weapon, whether the warrior is main tank or not. High delay weapons can hold aggro quite easily if they hit hard enough. Ask any paladin or shadow knight that has weilded a hard hitting, high delay weapon. They often find themselves out-taunting warriors with low delays, and without even casting.
As for guilds only using one main tank, that is simply not the case. On uber mobs, the fights can easily last longer than the duration of the defensive discipline. When defensive drops, that warrior is just another tank, no better than a shadow knight or paladin, except for a few more HP and slightly higher AC (if even that). In this situation, a solid guild knows how to rotate in another warrior to take over with a fresh defensive disc. As such, all warriors that are capable of acting as an MT against a high end mob should be equipped to hold aggro, however they do that.

