I have noticed that many malware engines pick up files now do the fact they are relatively unknown. I have had issues with Spriter and Construct 2 because the malware engine we use detected that they are files that are not well known and so blocked them. Not saying it is the case with your's but if you dig into the logs it should tell you why it blocked it.
It's definitely the page itself and not the file that Bitdefender is having an issue with. I downloaded it anyway and the file is clean. I don't know if there's a real issue here or just some aberration like you've said. I couldn't find a log of any kind to get details on the issue.
I'm currently getting a hard crash in C2 when trying to import a boned model. I've verified that all of the bones and png files are named and am using r119 and the 2/15 update for Spriter. Are there any issues I should be aware of that could cause this?