Personally, I think you're good so long as you don't charge money- because that's what 'commercial' literally means.
If you post something on Twitter. Facebook or an online portfolio- that equally counts as 'publishing', but nobody would see that as commercial.
It's always important to consider the intentions of the owner of the assets. When people say "For personal use only" this tends to mean "Yes, you can use this, but if you make money off our work, we want some of it!"