$150k to show up and do 1 hour of hosting for a month is not a bad gig at all for Bam but I'm sure someone got into Bam's ear about the Mr Naked stuff that happened and got him scared to come back and be affiliated with the show. It doesn't look good, considering Bam also interviewed Mr. Naked and was friendly with him. Bam has been trying to rebuild his reputation for years after all the alcohol abuse, rehab, and Jackass fallout. He's been doing a great job, and this Mr. Naked thing is a huge setback for his public relations.
Now, in reality, no one cares about Bam/Mr. Naked cause only maybe 20,000 people watch Fishtank, but it could be a major setback if the right people wanted to clip it and make it look like Bam knew about his past and was cool with this dude.
edit: welp I wrote all of that just to find out Bam is still the host and is just doing something else today lol