The argument is "Trust DDG". That argument is being attacked as "DDG's founder has done bad stuff in the past, it's likely DDG will do bad stuff, so I won't trust it". That seems to be attacking the argument to me, thus not an ad hominem.
[My opinion on trusting DDG] - [Reason for my opinion on trusting DDG].[More information about the reason]
In this case, because I don't use the "personal attack" to reach my conclusion that the person was wrong, I don't think it would be a case of argument ad hominem.
But if someone read it like this:
[One reason for my opinion on trusting DDG] - [Another reason for my opinion on trusting DDG].[More information about the second reason]
Then I am using the "personal attack" to reach my conclusion that the person was wrong, so I think it would be a case of argument ad hominem.
My comment wasn't written very well, and I'll try to write better comments in the future. Not that adding an ad hominem to a valid argument makes it invalid, I guess?. But it's still good to avoid fallacies, and to write one's comments so they're likely to be understood the way one meant them.