Not quite.

It is possible to go to the arrival gate - but there is only limited signage on arrivals level (level 2) as everyone is moving to either immigration or transfer. Arrival gates are not promulgated and so you may not know which gate your colleague is arriving. Arrival information is limited to baggage claim belt and customs exit door. However, THAI and AOT staff may be prepared to tell you which gate an arriving aircraft is deplaning at, and then you need to be familiar enough to locate that gate - if you get it wrong, you risk mis-connecting.

Note too, that if you can't interline your bags CX to TG, then after you have retrieved them and re-checked them, you'll be on Level 4 (departures). It is possible to descent to Arrivals (Level 2), but you'll be going like a salmon against the flow, and might (possibly) be stopped by security.

So, my personal view is that it is lower risk to simply arrange to meet on the departures level (4) - either in a Lounge if you have access, or coffee shop or restaurant. From there you can go to the departure gate at the appointed time.....

See map here: http://www.thaiair.com/thai-services...nformation.htm