If there was an ulterior motive for the delay, I'd guess it's Waze.

If Lisk can be officially bought and sold on April 11, I've heard a lot of people express that they want to dump some Lisk for Waze since the first day of that ICO is April 12, and you get a 20% bonus on that day only.

If you support Lisk, this is probably a good thing.  ICO investors might be less likely to dump their Lisk if they don't have a good reason for the funds.

NOTE: Yes, I have a Waze signature.  I support both projects which is exactly why I've been seeing people talk about both projects. I  follow both communities.