You don't squib is to the 30-40.
Let's break it down looking at the replay. KC had:
- 5 guys around midfield
- 3 guys at the 40
- 2 guys at the 20
- 1 guy on the goal line
The play would have been to squib it over the guys at the 40 and split the guys at the 20 so it bounces and the return man has to come up and field it around the 10-15 yard line.
The coverage team is farther back than usual, so let's say the returner is able to bring it out to the 30-35 yard line, but it takes him 4-5 seconds to do that, and unless he's smart enough to declare himself down at the first sign of trouble, you could even string it out to 6-7 seconds if it takes a while to stop forward progress and bring him down, or even longer if he tries to get tricky and cut back across the field.
There are a lot of ways the return man can screw it up!
Most likely, he's tackled at the 30-35 yard line at :08. Then KC is in a bind. They can run the quick-hitter to Hill over the middle to get to around midfield at :04. Then what? Either another quick-hitter to try to get another 8-10 yards and hope they play is over before :00 or the Hail Mary.
The improved likelihood of winning in that scenario is worth the small risk that the returner breaks one.
Edit: there's also a chance the returner panics and gives himself up immediately at the 10-15 yard line. This keeps the same amount of time on the clock for Mahomes (yes, you can "give yourself up" and the play just ends immediately without time coming off, kind of like a fair catch) but is also, of course, preferable to them getting it at the 25.