I dont think its played that badly. First read is that this villain isn't playing a $25 stack so hes very likely not a regular. These guys tend to be playing with their entire roll or whatever they ran up at 10nl etc that night. I play 25nl cash on Stars too. (I've checked, I have only one hand on you)

On flop I would give him a  range of flush draws (random 78s, 89s, T9s/pocket pairs (88-JJ?) and some random broadways hes got stubborn with. If you bet here, chances are he calls one street (if your lucky) with pairs and also calls with draws. These recreational players tend not to bet their draws, they just call regardless of pot odds. I like a flop check here as we can bet turn/river against pocket pairs and you may induce a spazz out (everyone at 25nl barrels when you check out of position).

Turn – Against a good reg I would maybe check again, but against this player I would lead for $7.50 and shove any not flush completing river. 

River – As played and with this river, folding to raise is optimal imo. I would probably c/f as this villain will check all hands you beat (recresational players want a showdown) and he has very few hands that need to bluff as most of the semi bluffs hit the river…

If all the draws missed I would maybe bet 1/3 pot (hoping to get called by his PP and induce a spazz shove by missed draws, he will also jam all sets)

Hope this helps. Knowing who your playing against and their tendancies is everything