dA, like virtually all other major companies in the US, will only support the most widely used browsers. Since Maxthon doesn't have even 1% of the total browser market share, they're not likely to consider supporting it directly. Unless it gets to around 2% or more and remains consistent, you're going to have to wait or use something else. You also can't expect a major support upgrade until a complete site overhaul, as there are countless features dA would have to research differences and create fixes for if necessary, which is best done during the coding phase of an upgrade, not after.
I don't think that Maxthon is officially supported by deviantART as Maxthon is a Internet Explorer (Trident) based browser that uses very little resources with less plugins.
However, the compatibility of Trident and Webkit (introduced in Maxthon 3) engines rely on the compatibility of which versions of Internet Explorer are supported by deviantART. And as such, dA currently supports IE 8 and later.
If Maxthon compatibility is set to Internet Explorer 8, then it should work.