The WHOLE issue that keeps getting repeated with bot farms is that small amounts may not have a big effect on one account, but when it's 1000s of accounts that adds up.
The entire discussion yesterday in mavs on packs in chests (1/20k chance for a bronze acct) may not be a big deal for any single account but when it's 1000s of accounts, it's 20k packs per week being given away.
The exact same logic applies here. If you're against packs in chests, you should logically be against sps for free (any amount for any period of time). If 100 sps is enough to be meaningful to a new account, then it's enough for a bot to benefit from it. So either 1) this is useless to new accounts and so why bother or 2) it's useful for new accouns and bots will exploit it.
The difference is that it requires a $10 spellbook purchase to get this short term delegation. Bots can already get 8x more SPS for a month for less than 100 DEC. They aren't going to pay $10 to create new accounts for something they could get a better deal on for existing accounts for ten cents. This proposal is just aiming to make sure new players aren't forced into immediately figuring out SPS and forking over more money to start playing.