I tried the PBR before I looked into R3's routing table. With R5 having a point-to-multipoint configuration R5 also announces 154.1.0.5. Now - look at R3 routing table:
C 154.1.0.0/24 is directly connected, Serial1/0
B 154.1.5.0/24 [20/0] via 154.1.0.4, 21:18:50
O 154.1.0.5/32 [110/98] via 154.1.0.4, 00:23:50, Serial1/0
There is a longer match for 154.1.0.5 through R4, the directly connected network for 154.1.0.0 ...routing rules state take the longest match.