Since Horn Exchange is not yet open for use and the team is moving very slowly, I don't think it's a secure exchange, not even your fund is safe here. It is in maintenance mode and the team has not yet publicly opened the detailed documentation of the exchange.
They have shown an irrational reason for not launching the Horn exchange is the volatility and fees of the current crypto market. I think those who trade crypto also have the ability to pay fees. This cannot be a reason for the launch of the exchange.
Another reason I give the exchange a bad rating is because of their team, they are very slow and they have not published any detailed documentation about the exchange, and there are many questions about their roadmap.
Overall, According to the recent announcement of the Horn Exchange, they may be online soon, although they have been saying this from the beginning but have not released it yet.
I would suggest everyone to refrain from using this exchange because I find it very suspicious and I have some doubts about whether they will be able to do it online at all.