Never use any branches you've applied anything to.
Look at it this way...
Have you sprayed the branch with anything:
- No: You can use it
- Yes: You can not use it
Once a plant has been seeded, so long as it hasn't been sprayed with anything, you can use the bud just fine to smoke. I do it all the time. I have three jars of bud curing after a seed run right now. A few jars curing a seed run is common for me every few months or so.
Again, so long as you haven't sprayed the seeded plant, you're good.