He is trying to be nice. But if Person A-Trump is honest and has been telling the truth and Person B-Biden is a known liar, plagiarizer, a person of low moral character who would you TEND to believe Person A or person B?
When I am presented with opposing points of view each having convincing argument I would indeed ‘tend’, be swayed, to believe the argument that is most probable... and not necessarily the most compelling.
But when I am presented with a REAL outcome/result of a contest without knowing all the processes/actions that had influenced and led up to the outcome... but now having to hear argument BETWEEN opposing sides instead of between opposing views...
then I would not use ‘tend’ in my expressed belief. I would instead make a more fitting(sapient) expression of belief drawn from that which is most compelling AND most probable.
“I TRULY believe the election was stolen!”
In others words... Rev Graham punted.