Perez is under pressure this weekend. He needs to win the race for Red Bull with Verstappen having a significant grid drop in regards to engine parts. If Verstappen can get some points he'll have a good result, so it's up to Perez to compensate.
If Perez crashes out again at a crucial time, his seat will be lost for next year if not for this year. Maybe putting Lawson in and getting him up to speed fast is worth more to Red Bull than Perez fighting with Hulk for P9 - P10.