That suggestion (of your lecturer) seems nigh-on incomprehensible.
Aircraft stability and AFCS appears to be pertaining to matters such as use of a yaw damper, up to full fly-by-wire stability augmentation, depending upon the degree of AFCS authority and amount of stability you want to maintain.
TCAS is, as I'm sure you know if youy already studied it, and autonomous and/or cooperative warning system for avoid ground impact or midair collision. Almost entirely dominated by considerations of aircraft performance (what RoC/RoD can I obtain/maintain) and almost entirely unaffected by stability and handling concerns.
The only MINOR link I could get was if someone has an autopilot mode actually directly engaged with TCAS (such that the aircraft would automatically respond to a TA or RA, without pilot input).
AFAIK no-one does that; I believe all responses to TCAS RAs and TAs has to be crew-initiated. (But I'd be intrigued to learn otherwise)