Great follow up question
That scenario wouldn't work because the Requirement Clause (in bold) on Hustled is: Boot your Grifter and increase their bounty by 1 to gain 2 ghost rock.
Since you can't do the 'increase their bounty by 1' part, the requirement clause cannot be fulfilled, which prevents Hustled from being played on Ol' Howard.
You would need to have a separate Grifter that: 1) can be booted, and 2) be able to have their bounty increased. You're absolutely right, the adding of bounty is something that must be performed.