Should service members enrolled in SFL-TAP still be included in daily unit tasks?

NO. Unless it's after TAP has ended for the day. I'm seeing all types of service members try to get their life together after the military and some of them are lost because they were pulled in different directions when they should have been at TAP paying attention to what was about to come their way. In some states, unemployment lasts 6 months. Then what? Do you have your certificate of eligibility for the GI Bill? Oh, never heard of it, you're now on HOLD with the VA and another semester behind? You probably should have been at TAP to learn this. Don't have a suit for your first job interview? There was probably a resource at TAP you could have learned about. Didn't get that civilian credential before you left the service? You could have learned about it during TAP. Don't know what LinkedIn is? You're LinkedOut. Now, I know all TAP classes are not created equally but there is some value - IF YOU ATTEND.

Soldiers can enroll in SFL-TAP 24- to 18-months prior to ETS/retirement...can commanders afford to lose these Soldiers for that amount of time and still maintain missions?

No. SFL-TAP is your location of duty. Anything you can find on SFL-TAP by the Army states, "Mission comes first." But, that's coming from the Army. SFL-TAP is a Federally mandated program created by Congress. Your commanders and Sergeant Majors don't have a say in your transitioning out of the Army. It's a program designed to help you get a job and not be another statistic when you ETS. Damn your unit, damn your CoC, damn your squad leader, damn your team leader, because they won't do a damn thing for you when you're out. All they want is to keep their trackers green.