If there had been infomercials to run, the station would have run them. The logical conclusion is that WJKT wasn't paid to run any this afternoon, so it took the filler feed from Fox instead. What is it about the relationship between infomercial producers and television people that you fail to grasp? Certain blocks of air time when very few people are expected to be watching are made available, for a price, to infomercial producers. In fact, if they pay enough money -- as the Project Smile cleft-palate hucksters do -- they can even get their pitches aired in a more desirable slot, with the money they pay for that privilege exceeding what the station could have made by showing the regular syndicated programming. In this case, with COVID-19 fears having paralyzed most of the sports world, Fox had no new sports programming to offer its affiliates on a weekend afternoon other than NASCAR's closeted Klansmen playing a video game and old sporting events that anyone with the slightest interest in sports had seen before.
WJKT wasn't going to make much money selling advertising for that sort of dung-heap, throwaway fare, but because no marginally legal "charity" or snake-oil sales company had come forward with enough moolah to buy the time, the station had no choice but to shovel Fox's slop into the trough, and forget about it. Ratings have less than nothing to do with this; it's purely a matter of money.