Doubtful, but possible.

He was able to get an idle for 30 seconds.

It would be best to tune the engine up and then look at the glow plug AFTER it is running and idling.

Once an engine is getting fairly close to being properly tuned, I'll let it idle with the ignitor installed.

After about a minute of continuous steady idle, I'll remove the glow plug ignitor.

If there is an audioble DROP in RPM's then I'll lean the engine again, re-install the ignitor and try again.

If I can get to the point that removing the ignitor causes almost NO drop in RPM's after this repeated testing, I - KNOW - the glow plug is just fine.

However if there seems to be absolutely no way to keep the same RPM's when the ignitor is removed, after repeated adjustments, then I know that there may be a problem with the glow plug.

That is not necessarily to say the glow plug is bad ( the engine IS running after all!!! ) but it may not be in the correct heat range for the fuel being used.