Maybe only an afterthought - but if you want to leave the Dragonborn DLC for a while, then some radiant quests can send you there - even before you speak to the Greybeards and find out that you ARE Dragonborn. I know Thieves Guild quests can send you there and the Dawnguard sent me there for a crossbow schematic as well...

And the problem is....????

If I'm not wanting to visit Solstheim until I'm a higher level then its a bit stupid that radiant quests send you there before your character has even heard of the place.

Well, technically you already know abot the existence of Solstheim, what the DLC does is giving you access to it. For example, you know that the imperial city exists but you can't go there, same with Solstheim before the DLC.

How is this a bug? Am I missing something?