I too was a varsity U of Guelph male runner on the program in the mid to late-2000's. I will state now that i saw nothing that would violate any code of conduct, harassment or rules of sport issues from Dave. He was also a mentor to me, and incredibly impactful in my life. Did he get super passionate / pissed off / ultra-competitive at times? - you bet! Did this piss off some people on the team ? - yep. Did he try (at times) to perhaps work the system to help support his athletes? Maybe - but nothing here would require a leave of absence. I have heard he is dealing with significant personal issues beyond anything to do with the team - but again, hearsay.
I too am watching this remotely and trying to figure out what exactly is going on, beyond a large amount of rumors flying around. But, obviously, none of us on the team (or at least me) at that time (and this is true of any team situation) truly know the truth of what is going on with every single relationship on the team, or between staff, or between coaches and athletes. If something inappropriate happened during any era, i feel so, so bad for that athlete, and justice should be served. That said, if this is nothing more than rumors, then i feel so, so bad for DST and his family and the work he has put into Guelph running and running in Canada.