You want his thought process before it all went to hell? Fuck if I know man, because none of it makes any sense to me. Malfoy's murder attempts nearly killed people under his protection twice and Dumbledore never acts which is beyond baffling.
I've always had a theory about why Dumbledore seemed so cavalier with his students safety, and while there's absolutely no evidence for it, there's also no evidence against it and it explains a lot. It's also cobbled together from a mix of info from the books and movies, so take everything below with
several grains of salt.
The theory is as follows: Hogwarts isn't the safest place in Magical because of Dumbledore, it's the safest place in Magical Britain because the founders put some downright terrifying protections in place for the students, up to and potentially including either precognitive or retroactive intervention making it impossible for a student to die barring some very specific and unusual circumstances.
The justification for this belief is as follows: Despite the horrifying lack of safety features, there are exactly 3 known cases of students dying at Hogwarts. The first example was Slytherin's heir using a monster that said founder had placed in the castle, presumably resulting in it being inside of the protections and not having to worry about overcoming them. The second time was during a potentially lethal tournament which the student in question had volunteered for, and even then they weren't killed on school grounds, just moved off of school grounds. Finally the third instance was the Battle of Hogwarts, where not only was Hogwarts not being used as a school, but it also opened with the castle being attacked by the Elder Wand itself (which cracked under the strain!).
While Hogwarts is operating as a school we never see a student die on school grounds from anything that wasn't deliberately included as a method of doing so by one of the founders. This is despite everything from the moving staircases to the dangers of improperly preformed magic presenting more than enough opportunities for an 11 year old to accidentally kill themselves.
If (and I'll admit that it's one hell of a big if) the above speculation is accurate, then Draco would present no real threat to any of his fellow students due to not knowing about the protections. In fact, this could even be a case of Dumbledore deliberately keeping the protections secret because of the loophole presented by removing students from school grounds before killing them. As long as nobody knows about the protections, nobody can try to circumvent them.
Once again, everything I've said here only has slightly more basis than most conspiracy theories, but it does at least provide some sort of explanation.
Edit: resolved autocorrupt issues