The 21-year-old was dismissed after 36 minutes for a second yellow card and the Foxes never looked back, forging ahead through Youri Tielemans in the 59th minute before Jamie Vardy sealed an emphatic win with two late goals.
Despite Leicester's dominance before Maitland-Niles' dismissal, Emery insists he was happy with how his side were performing and believes they could have won had numerical parity remained.
"We worked, we prepared our game plan and [when it was] 11 v 11 the match was going like we prepared," he told BBC Sport.
"For me the first yellow card should not be one. It has affected our game plan a lot. One player less is difficult.
"Today the reason [for losing] is the red card. We will continue, we will not look at the table. The Europa League is a big motivation for us."
Leicester, meanwhile, are still in the hunt for a seventh-place finish and a potential Europa League spot, and boss Brendan Rodgers was delighted with his side's dominant display.
"Firstly our defence was nice and aggressive and we pressed the game really well," he told Sky Sports.
"When it was 11 v 11 I thought we were the better team. I'm very pleased we got our reward for our hard work."