Lore skill specifically won't hinder taming gains. If they do I too would like to see the proof that lore itself was responsible. I think it was the total skill used, but interpreted as the lore skill slowing down gains when it could have been any skill at GM having the same result. Hope that makes sense
However any skills you have on a template during training will increase the total skill points you're using and
that could slow down your GGS gains. They might not, as you may only have taming and lore on your character, but the more skills you have and the more skill points you have used, the slower gains will be generally speaking.
Just bear in mind that lore will affect pet control, vetting success and stable slots, so you wouldn't want to just soulstone it off without a thought hehe.
Wenchy