I could well be hyperallergic after years of wincing at gratuitous unpleasantness in HN comments (edit: and, to be fair, having contributed my own share of it). In person, of course, tone of voice would reveal everything about "ummm...".
Either way, please understand that the intent behind comments like this is in no way personal. The idea is to send feedback signals into the community about the kind of discourse we want to cultivate.
You're microoptimizing. Spending time to complain about an "um" or and "uh" which had no semantic content implied other than what um or uh normally means is pointless. You can't micromanage every conversation, nor should you. Focus on outright negative comments. mine was surprise and disbelief (which was later rectified by data). System working as expect, no SNAFUs!
If it was a snotty 'ummmm', I personally would object to it in real life, too. And I think others would as well. Also, you don't need 'ums' in writing.
Notice that I actually had a question and it was answered in the thread, which I acknowledged.