"For now, custom models and artwork sit firmly in the “use-at-your-own-risk” category, but we’re keeping an eye on them. We can’t optimize for assets we don’t develop, and if they do become a concern for any reason in the future (ie. they provide measurable player advantage), we’ll take action based on the stance we just laid out.
Gray areas aside, there are definitely applications which are just not okay, and while the number of players in this space are very low (think a fraction of a percentage), we remain vigilant and hand out punishments to those who show patterns of consistent abuse."
Still a better stance that Valves which was to just break every custom mod for Dota 2.