Kk without reading any comments, heres my thing:
Did he deserve it?
We can't be sure. There isn't enough to be told about Thistleclaw. Yes, he trained in the DS, but so did ivypool, blossomfall, birchfall, etc. However, contradicting what i just said, he accepted the evilness from the DS instead of slowly rejecting it. Bluestar described Thistleclaw as bloodthirsty and cruel, but we don't know if that is true. Bluestar had been mentally unstable ever since her mother and sister had died. Perhaps she twisted it, or maybe she's right. We never saw Thistleclaw up close and personal. Yes, we saw him interact with Snowfur and Bluefur, but what was going through his head?
Thistleclaw trained Tigerpaw (soon to be the infamous Tigerstar) to be fierce and relentless, as shown in Scourge's manga. Thistleclaw egged him on as he beat up a kittypet kitten, but Bluefur, deputy at the time (i think), forced them to stop. All in all, this reveals that Thistleclaw had been influencing Tigerpaw badly, thus this makes him one of the cruelest cats in history. Now is that bad? Kinda.
Maybe Thistleclaw didn't realize how horrible Tigerpaw had grown as he trained him. Maybe he was blinded by ambition, much like Tigerclaw.
Idk man
My train of thought just disappeared.
Ill read the other comments now