Let's understand this thread and boil it down to its core components.
In recent polls, Biden leads the Democratic pack and polls also indicate that Biden beats Trump, who is up to 12,000 false statements made since inauguration, by double-digit margins. As such, the OP feels it is his "job" to attack Biden on the criteria that Trump is weak. Trump did that in 2016 -- the guy who was woefully dishonest and acted in a criminal manner, coined "crooked Hillary."
Yes, Biden makes Gaffes and has been doing so for decades. That isn't a sign of dementia. The key takeaway is that Trump and his cult aren't attacking Biden on policy -- because they can't. Biden is a defender of Obamacare and stated he would strengthen it if elected. He was also against the Trump tax-cuts, that failed to do everything stated it would do, and favors raising taxes on the rich. Biden also is a long-time defender of Medicare and Social Security. Contrastingly, Trump wants to eliminate Obamacare and is in court arguing it is unconstitutional. Trump and the GOP are on record stating that if they kept the House of Representatives in 2018, they would have cut Social Security and Medicare. Trump's view on taxes are clear: he wants high income people to pay less.
Challenged with Trump's indefensible positions on policies that directly effect Americans, the Trump cult create threads to change the subject. This is one of those treads. They want you to follow the shiny object.