Will the G1000 cut off transmission over 35 seconds?
I haven't tried it for real with PTT, but from what I know about G1000, it has generic protection against any stuck keys (including those on remote keypads/panels). When a key is detected to be pressed for longer than about 30-35 seconds, it is declared stuck and the respective CAS message appears on the PFD. It is then temporarily disabled; however, when another press is detected, it will work again. You can try it yourself with any of the bezel keys.

In this vein, it doesn't matter if you speak or not. If you keep PTT pressed for longer than 35 s, it will cut the transmission, but if you release and press it again, it will start transmitting again.

(Note that most normal keys in G1000 are activated on release (this is very common in software). But if a key is stuck or you hold it for long, its function will activate after about 0.6-0.8 s anyway. Some keys have 'press and hold' operation (e.g. holding frequency transfer for 2 s tunes in the emergency frequency 121.5), and it will also execute after the elapsed hold time. And only much later the key will be declared stuck.)