He wasn't Trump and was associated with the guy before Trump. And that's pretty much it. The idea Biden was thought of as particularly warm is false:
Anyone can post out of context clips to "prove" pretty much anything.
Case in point:
Hell, you could even say bizarro moments like "lying dog faced pony soldier" humanized Biden in some ways and endeared him to voters rather than make them think he was "cold." You have utterly failed to prove that premise. Indeed him having a bit of a temper at times supports rather than opposes my premise.