Yes, you are right. Actually, the fact you force your opponent isn't the problem (I don't think) but the fact that the presence of that piece might later give

Yes, you are right. Actually, the fact you force your opponent isn't the problem (I don't think) but the fact that the presence of that piece might later give p2 a free move, where previously they wouldn't means it doesn't work. Sorry, that's what I get for thinking I didn't need to figure out all the details carefully!