They're not likely to give you the illegal products you ordered if you went to pick them up, no.
In the 'love letter' they outline that they've opened a package addressed to you containing contraband and that you may contest the seizure. I have never had this happen as far as seeds go, but years back when I used to order prescription drugs online (without a prescription) I did have a package or two seized and received love letters instead of pills.
I suspect they have a general template that they use for the seizure letters and basically just fill in the blanks. One of the reasons the letter would outline your ability to contest a seizure is because while certain things are illegal to the general public and thus considered 'contraband', there are always exceptions depending on the individual involved and the item(s) seized. The most prevalent example of this would probably be for prescription drugs; while many people order them without a prescription from illegitimate over-seas pharmacies, some people actually do have a prescription and order from legit pharmacies. Customs wouldn't know who is who in the great majority of cases, so some people are going to end up having prescription drugs or other items seized that they're permitted to possess. If you can prove that the seized contraband isn't such in your case, and that you do have a right to it then you could contest the seizure and get your property.
