Found no issues during moderation, so, accepted. Since the cloud does not have any interaction with objects by default, I wouldn't consider the lack of direct interaction between the cloud and the block to be a bug. If preventing cheese with this mechanic is absolutely necessary though, a workaround could probably be made by setting the block's act as to 130.
yes, i'm aware of this and mention it in the comments. can't do anything about it, because as you mentioned the cloud has no collision. on the other hand this exploit can be used in clever level design.
There's a nasty exploit that you can bypass this by moving towards the block, jump off the cloud which “launches” the cloud through the block, and then you can get on the cloud on the other side of the barrier.
This is because:
-the cloud has no object interaction
-jumping off the cloud does not stop the cloud on a dime which that cancels its momentum (it will continue its inertia in the direction you last jump off).
-Only Mario riding the cloud deletes the cloud. If not riding, will not delete the cloud.