I am going to go counter to your article and most of the other people commenting.

Teddy Roosevelt succeed the assassinated McKinley and then was elected to his own full term in 1904. He declared that he considered the 1904-1908 term as his second term and vowed to not run again in keeping with tradition to that point that presidents only serve two terms. He was immediately boxed in as a lame-duck president and had difficulty getting his initiatives passed.

IF Biden does decide NOT to run, he should NOT announce it until the very start of likely primary election season. Announcing he will not run a second term will immediately make him a weaker president.