1. Some mention must be made of the fact that a space blimp is not only demented but also shows a rather poor understanding of simple physics - if it's in space, it won't matter if it's lighter than air.
2. One can only speculate as to the designers to whose libido Roll fell. Logically, these designers would have fetishes for misshapen creatures with chins (and bodies) reminiscent of Jay Leno. Roll appears to be clearly male but with breasts more or less glued on. You will need to suspend disbelief for David's purposes.