Yes. The "cam" kit he's talking about is the replacement for that eccentric bolt that's welded on from the factory, and if the alignment parameters have to be changed enough, that bolt needs to be cut off and replaced with one that's adjustable. I used to do alignments, and that place that you took your car to sounds to me like they really want to do the job right since they're willing to bother with cutting off the bolt that's welded on at the factory.
Most alignment places wouldn't want to be bothered with doing that, and therefore wouldn't have even told you about that, and would've simply set the specs as close as they can get them w/out having to touch that welded bolt, and taken your money. It's actually a poor set-up the way that Mercury has it with that bolt welded on there. And that isn't the fault of the alignment place that actually wants to perform the job correctly. It's Mercury's fault.
It sounds to me like you've found an excellent place for alignments. Like I said, I used to perform alignments myself, and trust me, I've seen some alignment people who always will cut corners and do the job halfway, just so they can get your car off the rack as soon as possible, and get to the next car. I'd have that place order the cam kit, and perform the alignment if I were you.
With some Marauders, the kit might not be needed. Atleast not for the first couple alignments. But there are three alignment settings, and sometimes only one of the three needs to be changed to get your front end back into spec, and it depends on which spec or specs out of the three that needs to be changed, and how far it's off from the factory spec as to whether or not that cam bolt will need to be cut off or not. So just because it wasn't needed for some peoples' Marauders so far, does NOT neccessarily mean that it doesn't need to be done to YOUR Marauder in order to get the alignment specs back where they should be.
Remember, there are good alignment guys and bad ones, and sometimes you can find both good and bad ones in one place (like the place that I used to work for). So if the place you took your Marauder to wants to do the job right instead of the easy way, then go back there and let them do that. I've never been a professional mechanic per say. atleast I don't consider what I used to do a "mechanic" position since I didn't perform repairs on cars. All is I did was perform alignments, and that's it. And the advice that I've given you here about your alignment, is based both on what you've told us here in this thread, and on my experience as an alignment person.