this isn't an unheard rule. several sites have a strict no-pets rule on stream because of their payment processor requirement. i also believe pets do not belong on an explicit camsite because of possible implications. mfc sure, since its more of a social site. but people are full on banging and fisting on CT. not to mention it opens you up to trolls asking you to be inappropriate with your pet
every site runs its shit differently. dont expect it to be okay on one site because it's no big deal on others. recommend reading TOS and following it like it's the bible.