He has the cavity filter in front of the amplifier on the prostick plus.
In that position the lower loss at the pass frequency is very beneficial compared to a SAW filter. (Or is the insertion loss similar? Don’t think so)
Edit: As you see in the post below, the cavity filter has only 0.5 dB of insertion loss. SAW filters have more around 2 dB insertion loss (COMPARISON OF 2 VERY SIMILAR 1090 Mhz SAW FILTER CHIPS)