Here is what admin said,
Most giveaway threads are no longer allowed in the Alternate cryptocurrencies sections.
That quote is for altcoins, not Bitcoin.
I've seen quite a few bitcoin giveaways in the past from gambling sites that seem to have stayed where they were so it's probably fine.
That would be my interpretation of the rules too, including (Bitcoin) free spins.
It might be worth looking at if there's a different way you could do it because a bump every few minutes (for example) might drown out anything useful on that board and if it gets too much the mods might react to it.
On Games and Rounds, that's totally acceptable. This thread has been doing it for 8 years:
Also if you think this promotion giveaway is good then come back daily and post on this thread for an additional 0.001 mBTC to your account.