I've never seen this happen. Players may choose not to play with you/her *again*... but that's a different issue.With Pathfinder Society gameplay, the other players at the table can refuse to play with a problem character, even if the character is viable according to Pathfinder Society rules and the GM is amenable.
I've seen five players at a table decide they didn't want to play with the sixth, ask that the player excuse themselves, and when the player did not, they went to the event coordinator to lodge a protest.
When told that they could either play the module or find another game, they all chose to play another game.
Some people take this game WAAAAAAAY too seriously.
I say Beast Master with Boon Companion. Or Find a PFS legal Archetype that grants a AC from level 1.
On Side-Bar: if players requested a Player Excuse themselves I would refuse to run the game for them. Though I don't do PFS as the only PFS community around me is full of Bigots and People who don't "play nice".
Cavalier (or samurai is probably better) does seem the best option for pfs at first level if you go human you can have point blank shot and precise shot and a camel which for 60 gold stats up like
N Large animal
Init +3; Senses low-light vision, scent; Perception +5
DEFENSE
AC 17, touch 12, flat-footed 14 (+3 Dex, +1 nat -1 size +4 hide barding)
hp 13 (2d8+4)
Fort +5, Ref +6, Will +0
OFFENSE
Speed 40 ft.
Melee 1 Bite +5 (1d4+6)
Space 10 ft.; Reach 5 ft.
Special Attack Spit ranged touch +4 target sickened for 1d4 rounds range 10 ft
STATISTICS
Str 18, Dex 16, Con 14, Int 2, Wis 13, Cha 7
Base Atk +1; CMB +8; CMD 19 (23 vs. trip)
Feats Light Armor Prof, Medium Armor Prof,
Skills Perception 2(+5)
SQ low-light vision, scent.
With an ac of 17 and +5 to hit with an effective 2 handed weapon it should serve well as a "tank" and the ranged touch debuf is just a nice bit of gravy as most pets have no ability at range. I'm fairly sure even PFS would have no problem with you describing it as a different creature as long as stat wise it fits the rule.
The problem with doing a camel or horse as combat pet is, again, the cramped spaces many many PFS modules end up with. Or urban environments where it's one thing to allow a druid or ranger's animal companion, but someone's pet dog or personal mount is a strict no-no.
Squeezing rules don't really hurt Camels and most other mounts. Heck, with the right teamwork feat and standard feats you can negate any attack aimed at the group.