I thought it was for the SBD peg, no?

It was always for a dual purpose, and part of that commitment to stakeholders is that the rewards be burned not sold, always being either buying pressure on STEEM (by using SBD to buy it) or neutral (by burning). For example, the SBD peg could be helped by using STEEM to buy SBD when SBD is undervalued. However, we don't do that because it would reintroduce the STEEM to the market, potentially hurting the price of STEEM.

I see that many other posts are now using burning (beneficiary to null), which is perfectly healthy and seems consistent with what you are suggesting. No one is required to support this or any other initiative. Vote how you like.

Finally, the biggest harm to the SBD peg at this point is the ever-decreasing price of STEEM. Cutting down on selling pressure can only help there too.