You might find this amazing, but getting fired for misconduct will not necessarily stop you from winning Disability Retirement. Delceg v. OPM is very clear on this:
“Removal for misconduct, however, does not preclude an appellant's receipt of disability retirement benefits if the appellant can show that he was disabled from performing useful and efficient service in his position prior to the effective date of his removal. See Powitz v. Office of Personnel Management, 82 M.S.P.R. 56, PP4-9 (1999). Further, relying on an employee's removal for misconduct as a basis for finding him ineligible for disability retirement under FERS is error. Burckley v. Office of Personnel Management, 80 M.S.P.R. 617, P13 (1999), modified on other grounds by Sangenito v. Office of Personnel Management, 85 M.S.P.R. 211, P15 n* (2000). Thus, the fact that the appellant was removed for misconduct and that he challenged his removal did not preclude him from seeking disability retirement.”
Getting fired for misconduct will draw the ire OPM adjudicators, and they won't want to grant you disability retirement. So you need an argument to explain to an adjudicator how the law provides for this.
This case is further support for the broader notion that Disability Retirement hinges almost entirely on the question of whether your disabling symptoms make it impossible for you to do your job.
Additionally, being removed can be a great outcome, even if it is for misconduct.
For example, say you have PTSD, and you hit your boss on the noggin. Now, he fires you for misconduct. You ask for disability retirement. OPM denies you because you weren't fired because of PTSD, but rather because you hit your boss on the head. But if you can argue the PTSD caused you to hit your boss, then bam! You win your case.