It's far of being bullet-proof, but should at least make deconners life harder without interfering with normal players too much.
I'd also make these non-gameplay-intrusive changes:
- Never, under any circumstance, allow to decon the last telenode/egg.
- Never allow to decon the last armory unless it's dead and waiting to explode.
- Never allow to decon any telenode if there is no reactor or no armory.
- Make om/reactor spawn with a small amount of health instead of 0 (just so it can stand 3 or 4 bullets right at placing it, to prevent it being unintentionally teamkilled).