Sealing Tiles and Cable routes in datacenter fire supression

Honestly, you won't be able to create a 100% air-tight room. No point in trying to. Most fire-suppression systems are deliberately designed with a certain amount of escaping air. That being said... The guy selling DuPont products should be the one to consult on this. You're the customer, not the service provider.

having gone through this exercise before you are in for lots of fun. Even if they get it right by their standards, your local fire marshal may have a different opinion. My recommendation is to try to reduce the number of cables going into that room, and then run the cables through the approved conduit. You won't be running any more cables though that conduit when finished so its usually advisable to make this a 10g switch to 10g switch line rather than expecting to use the conduit.