I'm no technique guru, but I disagree with most of that. I learned how to throw far by learning to throw a putter over 300', then throwing a driver exactly the same. I often throw putters on a hyzer, but with a clean throw you can throw flat or anny with a putter just fine (i.e. an anhyzer that carries and doesn't just turn and burn). Putters are tolerant of nose angle issues, but you won't get big distance with the nose up.
Clarifying my original post (apologies): A bit of hyzer *to get them to fly straight without drifting*. You can definitely throw putters flat and anny, sorry for the oversight.
Again, with the nose angle it's only slightly up. We can agree to disagree, but before you do go out tomorrow (or when you can) and focus on trying to drive a putter nose down like you would a Nuke for example.
Also you can work putters on a flat-nose, high-release style by pushing your thumb forward through the hit as opposed to snapping hard like a driver...they come out really similar and this may actually be an easier way to digest it mentally.
Maybe I should make a video? I feel like I'm not being super clear about all of this...it's in my head (and in my game) but not translating well.