Q:

Bounty by user with not enough reputation

I am not sure if it is correct to post this on the general Meta of StackExchange, but I encountered a strange thing on Security.
There is this post where a user offers a 100 bounty but only has a reputation of 23.
Now according to How does the bounty system work this should not be possible as ...

You must have at least 75 reputation to start a bounty, and at least as much reputation as the bounty amount.

which is certainly not true in this case. Is this a bug?

A:

Reputation is removed from the setter as soon as the bounty is set, as per the bounty faq:

The bounty award will be subtracted from your reputation when the bounty is started, not when it is awarded.

So that user would have had 123 reputation at the time the bounty was set, then the bounty award would have been subtracted immediately resulting the in 23 reputation.

A:

Nope. The user had 123 reputation at first. However, after setting the bounty, he lost the 100 rep, causing him to go to 23 rep. 123 rep allows him to set bounties. You can see the lost 100 rep in his reputation history:

