Yes, regulations around security tokens are strict. If you realized, Dreamr is the first security token to hold an STEO (Security Token Exchange Offering). There must have been some complications which led to the token sale being moved to their website or it might be a move to draw traffic to the website too.
Traffic doesnt mean nothing to Dreamr platform. Its wont be used by google for advertising. I think the reason token sales was moved to the website was because they wanted to ensure that only Non US investors purchase the tokens. Like you said, these are a different type of cryptocurrency, and strict rules have to be followed.
They've made a statement relating to this (though not directly) in one of their blog posts published earlier. It was stated that they've had talks with different exchanges but it seems like they weren't able to come up a mutual ground concerning the token sales.