Zonker's on point here, and the Seafoam bottle itself states it's "not to be used on vehicles with over 150,000 miles."
However, it's not definitive. Here's a link I've bookmarked with compression tests before and after seafoaming a civic
Seafoam on high mileage engine - Compression results - Honda-Tech
at 198,000 miles, I'm hesitant too!