Richardson was the biggest staunch, in that regard, for Weber State (13-7, 8-1).
After a pair of free throws from the Thunderbirds' Randy Onwuasor with 3:41 remaining, the Wildcats' lead was 73-65. Weber State freshman center Jordan Dallas hit two free throws of his own, then Richardson followed with consecutive 3-pointers.
Suddenly, the lead was back to 16 and the 'Cats were no longer in danger.
"We needed a spark. We really needed something to get us back going again," Weber State coach Randy Rahe said. "Those were really big shots."
Senior Jeremy Senglin led the way for the Wildcats with 23 points. Kyndahl Hill, who hit four free throws in the last two minutes, tallied 15.
Senglin's seven 3-pointers put him at 300 for his career. He is nine from breaking the Big Sky's all-time record.
Four of those treys came during a 21-0 run in the opening minutes as Senglin's accuracy pushed Weber State to the quick start. When the Wildcats went up 24-5, Senglin himself had 14 points.
"He's an elite shooter, that's just what he is," Rahe said. "When you've got that kind of weapon, that sometimes covers up some warts that you might have."
Southern Utah came into the contest with the second-leading scorer in the Big Sky as junior Onwuasor was averaging 23 points per game. Onwuasor finished with 27 on Thursday while John Marshall (15 points) and Brayden Holker (10) also finished in double figures.
"That first segment where they really got some separation, we just had a few too many breakdowns," said Southern Utah coach Todd Simon. "Turn the ball over, get some fouls — you get some of those against a great team like Weber and they're gonna make you pay."