The only choice here seems like mallin. If he's not a total donk, he presumably has outs, and it's possible he's even ahead with 2 pair. But I'm really not sure here what his outs are--clubs are probably weaker A or even straight. There are way too many scare-cards here, and having committed half his stack, if he has any reasonable chance, he's calling.
If I knew for a fact that it was a stone cold bluff or that he had <3 outs, I'd call, but I just don't on this board.
At $25 NL with no reads I'm calling a normal CR and going from there. Due to the size of the CR this isn't an option.
In theory the SB ought to be checkraising with a range here including air and big draws as well as his flopped sets and two pairs. In practice, at $25 NL, most opponents' range here will be two pairs and sets 80% to 90% of the time.
In theory, a larger-than-average CR should be a bluff trying to push you around a decent percentage of the time. In my experience, a bigger than normal bet like this is almost never a bluff at $25 NL.
I just dump this, make a note that he did it, and get ready to snap it off with any decent hand if he starts to make a habit of it.