Here's the section from the rule book:

Failure to Complete Game
Rule 108a. When a player is unable to complete a game because of disability, injury or
emergency, and another eligible player is not available, the team shall count the actual score for
the frames bowled plus one-tenth of the league’s absentee score for each remaining frame in the
game. (See Rule 118b for average information.) A player who leaves a game cannot return to
bowl in the same game.
NOTE: For computing score: Take actual score for frames bowled; credit 10 pins for a strike
or spare in last frame bowled. Add 1/10 of league’s absentee score for each of the remaining
frames. For example, if absentee score is bowler’s average less 10: Absentee score, 145;
1/10 of 145 = 14.5 X 3 frames = 43.5. Drop fraction and add 43 to actual score for 7 frames
bowled. The fraction is dropped after the total amount is figured, and not from each frame.

Looks like he only gets 10 pins for the eight frame, and what he gets for the other 2 frames is dependant on how your league calculates absentee scores.  If they use average - 10, then he should have only gotten 18 pins (not 19) for the last 2 frames.