Why SG does not return points if giveaway was deleted?

Why does it matter? They replenish for free anyway.

i dont think it's a real problem, the points are generated from finished giveaways not like gameminer form a countdown , so on sg points replenish really faster than GM, actually douring great bundle periods it's hard to use them all that they are back to 300

got them for "free" so meh

not a big deal

Gotta love that the question itself was never answered.
It was not implemented, AFAIK.

But they were right? I remember they were returned in SG 1.0 or was I imagining it?

This issue was introduced with SG v2 (early this year?) but has yet to be fixed. The previous version did refund points for deleted giveaways.