Yes, the Mine tag means Seeder mines work exactly as they do in the description of that tag in the gear section in all respects, including the necessary arming time. Seeder mines arm at the end of the Seeder's turn, so you can't immediately deploy one and knock someone into it, same as a PC can't do that. One of the main goals for the Seeder rebake in particular is that mines should work the same on both sides of the screen rather than having a bunch of weird exceptions that everyone has to juggle in their heads.